All Engineering Calculators
This page brings together every engineering calculator available on CalcEngineer in one organized directory. Browse the full library, compare related tools, and jump to the calculator that matches your task — whether it involves airflow, duct sizing, pressure drop, voltage drop, power calculations, load estimation, or other technical workflows.
Calculators are grouped by category below. Each tool is built around a fixed formula or decision model specific to its use case. Select a category to jump directly, or scroll through the full list.
HVAC Calculators
Heating, ventilation, air conditioning, cooling load, duct sizing, and airflow calculators.
HVAC Heat Load Calculator
Calculate heating requirements for residential and commercial spaces
CFM Calculator
Calculate cubic feet per minute for airflow requirements
Duct Size Calculator
Determine optimal duct dimensions for HVAC systems
Cooling Load Calculator
Estimate cooling capacity required for AC system sizing
AC Tonnage Calculator
Calculate required air conditioner capacity in tons of refrigeration
Fan Power Calculator
Estimate fan motor power in HP and kW for HVAC and ventilation systems
Velocity Pressure Calculator
Calculate velocity pressure in HVAC systems using air velocity for duct design and fan selection
Air Changes per Hour Calculator
Calculate ACH based on airflow rate and room volume for ventilation design and indoor air quality
Duct Velocity Calculator
Calculate air velocity inside HVAC ducts using airflow and duct size for round and rectangular ducts
Static Pressure Calculator
Calculate static pressure in HVAC systems using airflow, velocity, and air density for duct design and fan selection
Adaptive Comfort Model Calculator
Calculate thermal comfort using the adaptive comfort model based on outdoor temperature for naturally ventilated buildings (ASHRAE 55)
Thermal Comfort PMV/PPD Calculator
Predict PMV and PPD for offices, HVAC design, and indoor environment assessment. Based on ISO 7730 and ASHRAE Standard 55 thermal comfort methods.
Air Density Calculator
Calculate air density using temperature, pressure, and altitude with the ideal gas law for HVAC design
Air Velocity Calculator
Calculate air velocity through ducts, grilles, and openings using airflow and cross-sectional area
Aircraft Hangar Heating Calculator
Estimate aircraft hangar heating load based on hangar size, temperature, insulation, and infiltration for preliminary heater sizing
Animal Barn Ventilation Rate Calculator
Calculate barn ventilation rate by animal type, animal count, and ventilation mode. Estimate required airflow in CFM and m³/h for livestock housing.
Poultry House Ammonia Control Calculator
Calculate poultry house ventilation for ammonia control in CFM or m³/h using flock size, bird weight, litter condition, and ammonia target.
Archive Climate Control Calculator
Evaluate archive climate conditions using temperature, relative humidity, and dew point. Check whether storage conditions are out of range, marginal, stable, or tightly controlled.
Blower Door Test CFM50 Calculator
Calculate blower door airtightness from CFM50 and building volume. Convert CFM50 to ACH50, estimate metric airflow, and classify building tightness.
Boiler Efficiency Calculator
Calculate boiler efficiency using useful heat output and fuel energy input. Estimate efficiency in percent for hot water or steam boiler performance checks.
Boiler Feed Pump Sizing Calculator
Calculate boiler feed pump size from steam generation rate, blowdown, head, and pump efficiency. Estimate required flow, total head, and pump power.
Dust Collection System Sizing Calculator
Calculate dust collection system size from pickup airflow, machine count, and simultaneous use. Estimate required airflow in CFM and m³/h with a fixed design margin.
Duct Pressure Drop Calculator
Calculate duct pressure drop from airflow, duct size, length, and friction assumptions. Estimate total pressure loss, friction rate, and airflow resistance in imperial or metric units.
Duct Insulation Loss Calculator
Calculate duct insulation heat loss or heat gain from duct size, insulation thickness, thermal conductivity, duct length, and temperature difference.
Duct Friction Loss Calculator
Calculate duct friction loss from airflow, duct diameter, effective length, and duct roughness. Estimate friction rate in in. w.g./100 ft or Pa/m.
Fan Law Calculator
Calculate new fan airflow, static pressure, and brake horsepower using the three HVAC fan laws. Predict fan performance changes from speed, diameter, or density adjustments.
Fan Efficiency Calculator
Calculate fan efficiency using airflow, pressure, and shaft power. Estimate air power and fan efficiency percentage for HVAC fan performance checks.
Cool Roof Energy Savings Calculator
Calculate energy savings from cool roof coatings and materials. Estimate reduced cooling load, annual kWh savings, and cost reduction based on solar reflectance and climate zone.
Cooling Tower Approach Calculator
Calculate cooling tower approach from leaving cold water temperature and entering wet-bulb temperature. Estimate tower thermal performance in imperial or metric units.
Cooling Tower Calculator
Calculate cooling tower efficiency, approach, and range from hot water, cold water, and entering wet-bulb temperature in imperial or metric units.
Liquid Cooling Flow Rate Calculator
Calculate liquid cooling flow rate in GPM or L/s from cooling load and temperature rise. Check whether flow is too low, balanced, or too high for your cooling duty in Imperial or Metric units.
Heat Exchanger Calculator
Calculate heat exchanger heat duty using overall heat transfer coefficient, heat transfer area, and log mean temperature difference (LMTD) in imperial or metric units.
Heat Pump Size Calculator
Calculate heat pump size from design load and sizing margin. Estimate required BTU/hr, tons, or kW and classify equipment as undersized, well sized, or oversized.
CRAC Unit Sizing Calculator
Calculate CRAC unit size from IT load and room heat gains. Estimate required BTU/hr, tons, or kW and classify the result as undersized, well sized, or oversized.
HVAC Efficiency Calculator
Calculate HVAC efficiency from useful output and energy input. Estimate efficiency percentage, energy loss, and practical performance in imperial or metric units.
Delta T Calculator
Calculate Delta T (temperature difference) between supply and return air or water in HVAC systems. Estimate sensible heat transfer rate from airflow and temperature difference.
Chiller Capacity Calculator
Calculate chiller capacity from chilled-water flow and temperature difference. Estimate cooling load in tons, BTU/hr, or kW for imperial and metric units.
Chiller Efficiency Calculator (IPLV)
Calculate chiller IPLV from 100%, 75%, 50%, and 25% load-point efficiencies. Estimate weighted part-load efficiency in kW/ton or COP using the AHRI IPLV method.
Building Envelope Tightness Calculator
Calculate building envelope tightness from blower door test data. Convert CFM50 or m³/h at 50 Pa into ACH50 and evaluate airtightness for HVAC and energy performance.
Passive House PHPP Energy Balance Calculator
Estimate net annual energy balance in kWh/m²·yr or kBtu/ft²·yr using a simplified PHPP-style loss-versus-gain model. Screen transmission losses, ventilation losses, solar gains, and internal gains for Passive House design.
Net Zero Energy Feasibility Calculator
Estimate annual net energy position in kWh/m²·yr or kBtu/ft²·yr by comparing annual building energy use against annual on-site renewable energy production. Screen SURPLUS, NEAR ZERO, DEFICIT, or LARGE DEFICIT outcomes for building-performance feasibility review.
Cleanroom Air Change Rate Calculator
Calculate cleanroom air change rates based on ISO 14644-1 classification and room volume. Determine required ACH and supply airflow for ISO Class 1–9 cleanrooms.
Pharmaceutical Cleanroom Cascade Pressure Calculator
Estimate room-to-room cascade pressure difference for pharmaceutical cleanrooms using supply airflow, exhaust airflow, and room leakage tightness.
Ground Source Heat Pump COP Estimator
Estimate ground source heat pump COP from source and load temperatures using a fixed temperature-lift model with a performance factor.
Greenhouse Heating and Ventilation Calculator
Estimate greenhouse heating load, ventilation airflow, and required heater capacity based on covering material, dimensions, and climate conditions for year-round growing.
Glycol Concentration Calculator
Calculate glycol concentration for HVAC and hydronic systems. Evaluate freeze protection margin and determine required glycol volume for a target concentration.
District Heating Pipe Loss Calculator
Calculate heat loss from buried district heating pipes using cylindrical resistance model. Estimate linear loss, annual energy waste, insulation efficiency, and return temperature.
VRF System Sizing Calculator
Calculate VRF outdoor unit sizing ratio from connected indoor capacity and diversity factor. Evaluate UNDERSIZED, ACCEPTABLE, OPTIMIZED, or OVERSIZED conditions for preliminary VRF system design.
Psychrometric Calculator
Calculate psychrometric properties from dry-bulb temperature and relative humidity. Estimate humidity ratio, dew point, vapor pressure, enthalpy, and specific volume.
Enthalpy Calculator
Calculate specific enthalpy of moist air in BTU/lb or kJ/kg. Compute sensible and latent components, SHR, and total coil load for single or two state points.
Ventilation Rate Calculator
Calculate required ventilation rate using occupancy, floor area, and air distribution effectiveness. Estimate outdoor airflow in CFM, L/s, and ACH using ASHRAE 62.1.
Refrigeration Load Calculator
Calculate refrigeration load from transmission, infiltration, product, internal, and equipment heat gains. Estimate required refrigeration capacity in BTU/hr, tons, or kW.
Wine Cellar Cooling Load Calculator
Calculate wine cellar cooling load from transmission, infiltration, and internal gains. Estimate BTU/hr, kW, or tons for wine cellar equipment sizing in Imperial or Metric units.
Refrigerant Charge Calculator
Calculate total refrigerant charge for split-system AC and heat pump installations. Estimate additional charge based on liquid line length, diameter, and refrigerant density.
Superheat & Subcooling Calculator
Calculate refrigerant superheat or subcooling from saturation and line temperatures. Evaluate system charge readings for HVAC and refrigeration service diagnostics.
Grease Duct Sizing Calculator
Calculate grease duct size from kitchen exhaust airflow and target duct velocity. Estimate round diameter, rectangular equivalent size, duct area, and resulting grease exhaust velocity.
Sound Attenuation in Ducts Calculator
Calculate sound attenuation in ducts using duct length, attenuation rate, and elbow losses. Estimate total dB reduction and outlet sound level for HVAC duct systems.
Raised Floor Pressure Drop Calculator
Calculate raised floor pressure drop using airflow, tile size, free area, and discharge coefficient. Estimate panel free area, face velocity, and pressure drop in Pa or in. w.g.
Latent Heat Load Calculator
Calculate latent heat load from airflow and humidity ratio difference. Estimate moisture removal rate, latent cooling load, and dehumidification demand in BTU/hr, kW, lb/hr, or kg/h.
Sensible Heat Ratio Calculator
Calculate sensible heat ratio (SHR) from sensible and latent cooling load. Estimate total cooling load and understand the balance between temperature control and dehumidification demand.
Office Open Plan Cooling Load Calculator
Calculate cooling load for open-plan offices. Estimate total heat gain from occupants, lighting, equipment, envelope, and ventilation to size HVAC systems accurately.
Restaurant Cooling Load Calculator
Calculate restaurant cooling load from kitchen equipment, occupancy, lighting, envelope, and makeup air. Estimate total cooling load and load per area in BTU/hr or kW for dining and kitchen zones.
Hotel Guest Room HVAC Sizing Calculator
Calculate hotel guest room HVAC cooling capacity from room area, occupancy, glazing, lighting, equipment, and ventilation. Estimate required BTU/hr or kW per room for PTAC, PTHP, and FCU selection.
Server Rack Heat Load Calculator
Calculate server rack heat load from IT equipment power, rack count, PDU losses, and lighting. Estimate total cooling load and heat load per rack in BTU/hr or kW for CRAC, CRAH, and in-row cooling sizing.
Altitude Correction for HVAC
Calculate HVAC altitude correction factor using a standard atmosphere model to adjust sea-level assumptions for elevation
Retail Store Lighting Heat Gain Calculator
Calculate retail store lighting heat gain from general, display, accent, and decorative lighting. Estimate total heat gain and load per area in BTU/hr or W/m² for retail HVAC cooling load.
Warehouse Heating with Destratification Calculator
Calculate warehouse heating load with and without destratification. Estimate envelope, infiltration, and ventilation heat loss plus destratification savings in BTU/hr or kW for heater sizing.
Kitchen Hood Exhaust CFM Calculator
Calculate kitchen hood exhaust CFM from hood length, duty level, and cooking equipment type. Estimate required exhaust airflow and makeup air for Type I and Type II commercial kitchen hood sizing.
Makeup Air Unit Sizing Calculator
Calculate makeup air unit heating capacity from exhaust airflow, design outdoor temperature, target supply temperature, and energy recovery effectiveness. Estimate MAU BTU/hr or kW for commercial kitchen and industrial exhaust makeup air sizing.
Supply Air Temperature Calculator
Calculate required supply air temperature for HVAC heating and cooling systems from airflow, room temperature, and sensible heat load using the sensible heat equation.
Return Air Ratio Calculator
Calculate return air ratio and outdoor air fraction from supply, return, and outdoor airflow. Estimate recirculation percentage in CFM or m³/h for AHU mixing box design and ASHRAE 62.1 ventilation review.
School Classroom Ventilation Calculator
Calculate required outdoor airflow for school classrooms using ASHRAE 62.1. Enter room area, occupants, and supply airflow to check ventilation adequacy, ACH, and cfm/person.
Indoor Air Quality CO2 Calculator
Calculate steady-state indoor CO2 concentration using the mass balance model. Enter occupants, activity level, room volume, and outdoor airflow to check IAQ status, required ventilation rate, and cfm/person.
Humidity Ratio Calculator
Calculate humidity ratio (W) from dry-bulb temperature and relative humidity, wet-bulb, or dew point. Results in gr/lb and g/kg with dew point, vapor pressure, and degree of saturation.
Dew Point Temperature Calculator
Calculate dew point temperature from dry-bulb and relative humidity, wet-bulb, humidity ratio, or vapor pressure. Instant results with condensation risk assessment, dew point depression, and ASHRAE 55 comfort status.
Wet Bulb Temperature Calculator
Calculate wet-bulb temperature from dry-bulb and relative humidity, dew point, or humidity ratio. Instant results with evaporative cooling potential, enthalpy, and psychrometric analysis.
Specific Volume of Air Calculator
Calculate specific volume of air based on dry-bulb temperature, pressure, and humidity. Get results in m³/kg or ft³/lb for HVAC and psychrometric applications.
Coil Capacity Calculator
Calculate HVAC coil capacity including total, sensible, and latent capacity with SHR. Supports air-side and water-side calculations in BTU/hr or kW.
Cold Storage Door Infiltration Calculator
Calculate heat load from air infiltration through cold storage doors. Estimate sensible, latent, and total load in BTU/hr or kW for freezers and coolers.
Dairy Barn Cooling Calculator
Calculate required cooling capacity for dairy barns to reduce heat stress in lactating cows. Estimate total BTU/h or kW, sensible and latent loads, and ventilation needs.
Commercial Kitchen Energy Recovery Calculator
Calculate heat recovery potential, annual energy savings, and payback period for commercial kitchen exhaust energy recovery systems. Estimate recovered BTU/hr or kW, cost savings, and heat recovery density.
Condensate Pump Sizing Calculator
Calculate HVAC condensate drain pump capacity from cooling load, sensible heat ratio, and safety factor. Estimate condensate flow in GPH or L/h for AC and dehumidification systems.
Data Center CRAC Redundancy Calculator
Calculate data center CRAC redundancy, remaining cooling capacity after one unit failure, redundancy margin, spare capacity, and shortfall in Imperial or Metric units.
Daylight Factor Calculator
Calculate daylight factor, indoor daylight illuminance, and daylight adequacy in lux or foot-candles. Estimate natural light performance for rooms and glazing layouts.
Deaerator Vent Rate Calculator
Calculate deaerator vent rate, vent steam loss, and vent rate as a percent of steam load. Screen deaerator venting for oxygen removal and steam economy in Imperial or Metric units.
Dehumidifier Sizing for Pools
Calculate pool dehumidifier size, moisture removal rate, and recommended capacity for indoor pools. Estimate natatorium dehumidification load from evaporation and room conditions in Imperial or Metric units.
Natatorium Evaporation Rate Calculator
Estimate indoor pool evaporation rate and natatorium latent moisture load in lb/h or kg/h. Screening tool for natatorium dehumidification design based on pool area, water temperature, room dew point, and activity factor.
Museum Artifact Preservation Humidity Calculator
Estimate preservation-oriented relative humidity for museum collections based on current room RH, artifact sensitivity class, and seasonal control strategy. Screening tool for museum HVAC and conservation coordination.
Elevator Machine Room Cooling Calculator
Calculate elevator machine room cooling load, recommended cooling capacity, and sizing margin in Imperial or Metric units. Estimate HVAC cooling for elevator drive and control equipment rooms.
Energy Recovery Wheel Efficiency Calculator
Calculate energy recovery wheel sensible, latent, and total effectiveness from airflow and temperature/humidity conditions. Estimate ERV performance for HVAC energy analysis.
Mine Ventilation Airflow Calculator
Evaluate mine ventilation airflow in CFM or m³/s against a defined underground ventilation duty. Classify airflow as too low, marginal, recommended, high, or too high relative to the design target intensity.
Tunnel Ventilation Rate Calculator
Estimate required CFM, m³/s, or air velocity for tunnel ventilation. Compare results to low, moderate, high, or very high interpretation bands for preliminary tunnel design.
Transformer Room Ventilation Calculator
Calculate transformer room ventilation from heat loss and allowable temperature rise. Estimate required CFM or m³/h and compare results to low, moderate, high, or very high bands.
Ship Engine Room Ventilation Calculator
Calculate marine engine room ventilation in CFM or m³/s from engine power, heat loss factor, and allowable temperature rise. Estimate required airflow for combustion air and machinery heat removal.
Flash Tank Sizing Calculator
Calculate flash tank volume, flash steam flow, condensate flashing rate, and vessel size in Imperial or Metric units. Size a flash tank for condensate pressure drop and steam separation.
Steam Trap Capacity Calculator
Calculate required steam trap condensate capacity in lb/h or kg/h from condensate load, startup factor, and differential pressure. Compare against selected trap capacity with UNDERSIZED / ACCEPTABLE / RECOMMENDED / OVERSIZED sizing categories.
Fuel Oil Tank Sizing Calculator
Calculate fuel oil tank volume, storage duration, usable fuel volume, and reserve margin in Imperial or Metric units. Size a fuel oil tank for HVAC boilers, burners, and building runtime coverage.
Propane Tank Sizing Calculator
Calculate required propane tank size from connected load, daily runtime, refill interval, appliance efficiency, and fill level. Works in Imperial (BTU/h, gallons) and Metric (kW, liters).
Humidification Load Calculator
Calculate humidification load, moisture addition rate, humidity ratio increase, and HVAC humidifier capacity in Imperial or Metric units for winter air-conditioning applications.
Mold Risk Calculator
Calculate mold risk using indoor air temperature, relative humidity, and surface temperature. Check dew point, surface RH, and condensation-driven risk. Get an instant LOW, MODERATE, HIGH, or SEVERE result.
Grain Dryer Airflow Calculator
Calculate grain dryer airflow, airflow intensity, and required ventilation in Imperial or Metric units. Estimate fan airflow for grain drying, dryer throughput, and drying-air duty.
Silo Aeration Fan Sizing Calculator
Calculate silo aeration fan size from airflow target, grain volume, and static pressure. Estimate required CFM or m³/h for cooling, maintenance aeration, or grain-storage airflow planning.
Fume Hood Face Velocity Calculator
Calculate fume hood face velocity from exhaust airflow and hood opening area in Imperial or Metric units. Screen hood capture performance and laboratory exhaust conditions.
Laboratory Fume Hood Diversity Factor Calculator
Calculate laboratory fume hood diversity factor from diversified design exhaust and total installed hood exhaust in Imperial or Metric units. Screen whether the diversity assumption is low, recommended, or high.
Geothermal Loop Length Calculator
Calculate geothermal loop length, loop length per ton or per kW, and preliminary ground heat exchanger size in Imperial or Metric units for closed-loop HVAC systems.
Glare Index Calculator
Calculate glare index and assess visual comfort, discomfort glare, and glare severity for interior lighting conditions. Screen whether glare is very low, low, moderate, high, or very high.
Hospital Operating Room Airflow Calculator
Calculate required supply airflow for hospital operating rooms from room dimensions and air-change rate. Estimate CFM or m³/h with ACH screening bands for OR ventilation design.
Hydronic Balancing Calculator
Check hydronic circuit balance by comparing actual flow to design flow. Calculate flow ratio and deviation percent with instant balancing status for HVAC hydronic systems.
Pool Heating Load Calculator
Calculate pool heating load using pool surface area and heat loss per unit area. Estimate required heating capacity in BTU/h or kW for practical pool heating design.
Spa Heat Up Time Calculator
Calculate spa heat-up time from water volume, temperature rise, and effective heater output. Estimate hours and minutes to reach target temperature in Imperial or Metric units.
Radiant Floor Heating Output Calculator
Calculate radiant floor heating output in BTU/hr·ft² or W/m² using water temperature, tube spacing, and floor covering resistance. Screen preliminary floor output for hydronic radiant design.
Hot Aisle Containment Efficiency Calculator
Calculate hot aisle containment efficiency as a percentage of effectively contained hot exhaust air. Evaluate containment performance against engineering thresholds for data center airflow management.
Ice Rink Refrigeration Load Calculator
Calculate ice rink refrigeration load intensity by normalizing total refrigeration demand by rink area. Evaluate load severity against fixed engineering thresholds for hockey rinks and skating arenas in BTU/h or kW.
Library Book Storage Temperature Calculator
Evaluate library book storage temperature against a fixed preservation band of 60–68°F (16–20°C). Classify storage conditions as TOO HIGH, HIGH, RECOMMENDED, LOW / MARGINAL, or TOO LOW for preservation-oriented environmental review.
Window U-Value & SHGC Selector
Evaluate combined window thermal performance using U-value and SHGC. Classify fenestration performance as POOR, FAIR, GOOD, or HIGH PERFORMANCE for preliminary envelope selection in Imperial or Metric units.
Welding Fume Extraction Calculator
Calculate welding fume extraction rate using hood area, capture velocity, and extraction efficiency. Estimate required CFM or m³/h for local exhaust ventilation and source-capture design.
Waste Heat Recovery Efficiency
Calculate waste heat recovery efficiency (%). Evaluate heat exchanger performance, thermal utilization, and system effectiveness in Imperial or Metric units.
Vehicle Exhaust Extraction Calculator
Calculate CFM or m³/h for tailpipe exhaust capture. Estimate required extraction flow for workshops, test bays, and multi-vehicle facilities.
Parking Garage CO Ventilation Calculator
Estimate required CFM or m³/h for parking garage CO control. Compare low, normal, high, or very high ventilation demand based on garage area, vehicle activity, and allowable CO concentration rise.
Paint Booth Ventilation Calculator
Estimate required CFM or m³/h for paint booth overspray capture. Compare low, normal, high, or very high ventilation demand based on booth opening area, target face velocity, and booth type.
VOC Concentration Estimator
Estimate indoor VOC levels in ppm or mg/m³ from source emission rate, room volume, and ventilation dilution using a well-mixed steady-state mass-balance model.
Subway Platform Heat Load Calculator
Estimate subway platform heat load from passenger, train, tunnel-air, and internal gains. Compare results to low, moderate, high, or very high bands for preliminary platform cooling design.
Snow Melt System Sizing Calculator
Estimate the heating load for outdoor snow and ice melting from heated area and design heat flux. Supports metric and imperial units with load categories for preliminary hydronic or electric snow-melt system design.
Radon Mitigation System Sizing Calculator
Estimate required CFM or m³/h for ASD fan sizing from treatment area, slab leakage class, and sub-slab communication condition. Preliminary radon mitigation airflow sizing for active soil depressurization system design.
Electrical Calculators
Voltage drop, wire sizing, circuit breakers, power calculations, battery sizing, and electrical safety tools.
AFCI Zone Calculator
Check whether AFCI protection is typically required based on the selected room, zone, or circuit context for code guidance and electrical planning
Antenna Gain Calculator
Calculate antenna gain using directivity and efficiency. Convert the result into dBi and dBd for RF design, antenna comparison, and link budget analysis
GFCI Protection Requirements Calculator
Check whether GFCI protection is typically required based on the selected location, equipment, and installation context for code guidance and electrical planning
Breaker Size Calculator
Calculate the recommended circuit breaker rating from load current using continuous-load adjustment and standard NEC breaker sizes
Voltage Drop Calculator — NEC (Copper)
Calculate voltage drop for copper conductors using NEC Chapter 9 Table 8 resistance values for single-phase and three-phase circuits
Voltage Drop Calculator — NEC (Aluminum)
Calculate voltage drop for NEC aluminum conductors using the K-factor circular-mil method for single-phase and three-phase circuits
Voltage Drop Calculator
Calculate voltage drop using conductor resistance, circuit current, run length, and system type for copper and aluminum conductors
NEC Service Entrance Size Calculator
Calculate residential service entrance size per NEC Article 220. Compare Standard vs Optional Method, include EV charger and heat pump loads, find minimum service ampacity.
Arc Flash Energy Calculator (NEC)
Estimate arc flash incident energy at working distance and screen hazard severity using a fixed NEC-oriented decision model
Battery Bank Calculator
Calculate required battery bank size in Ah, Wh, kWh, and battery count using load, runtime, system voltage, depth of discharge, and efficiency
Battery Bank Sizing for Off-Grid
Calculate off-grid battery bank size from load, autonomy, system voltage, depth of discharge, and efficiency. Estimate required Ah, Wh, kWh, and battery count.
Microgrid Battery Storage Sizing Calculator
Calculate battery storage capacity for microgrid systems. Estimate required kWh, battery module count, minimum power rating, and discharge duration from load, autonomy, DoD, and efficiency.
Microgrid Stability Estimator
Estimate microgrid Stability Index for islanding and control design. Classify as UNSTABLE, MARGINAL, STABLE, or ROBUST based on source support, load demand, inertia factor, and stability margin.
Cogeneration CHP Sizing Calculator
Estimate CHP system size (kW) using facility electrical demand, usable thermal demand, and heat-to-power ratio. Classify as SMALL, STANDARD, LARGE, or VERY LARGE for preliminary cogeneration screening.
Generator Fuel Consumption Calculator
Estimate generator hourly fuel consumption in gal/h or L/h from rated output, operating load fraction, and fuel-consumption factor. Screen result as LOW, NORMAL, HIGH, or VERY HIGH for preliminary fuel planning.
Generator Sizing Calculator
Estimate generator size in kW from connected running load and sizing factor. Screen result as SMALL, STANDARD, LARGE, or VERY LARGE for preliminary generator capacity planning.
Battery Capacity (Ah) Calculator
Estimate required battery capacity in Ah for a DC load and target runtime. Adjust for depth of discharge and system efficiency. Screen result as SMALL, STANDARD, LARGE, or VERY LARGE.
Battery Life Calculator
Estimate expected battery runtime in hours for a DC load. Adjust for depth of discharge and system efficiency. Screen result as SHORT, MODERATE, LONG, or VERY LONG.
Solar Charge Controller Sizing Calculator
Estimate required solar charge controller current rating in amps for off-grid PV systems. Size by PV current, parallel strings, and design margin. Screen as SMALL, STANDARD, LARGE, or VERY LARGE.
Solar Panel Tilt Angle Calculator
Calculate the optimal tilt angle for fixed-mount solar PV arrays at a given site latitude. Year-round, seasonal, monthly, two-season, and verify-existing modes. Latitude regime classified as EQUATORIAL, LOW-LATITUDE, MID-LATITUDE, HIGH-LATITUDE, or POLAR.
UPS Battery Runtime Calculator
Estimate UPS battery runtime in minutes for a connected load. Adjust for depth of discharge and UPS efficiency. Screen result as SHORT, MODERATE, LONG, or VERY LONG.
UPS Sizing Calculator
Estimate required UPS capacity in VA for a connected critical load. Size by connected load, power factor, and design margin. Screen as SMALL, STANDARD, LARGE, or VERY LARGE.
Transfer Switch Sizing Calculator
Size a generator transfer switch in amps per NEC Article 702. Apply the 125% continuous-load factor and select the next UL 1008 standard rating. Screen as SMALL, STANDARD, LARGE, or VERY LARGE.
Soft Starter Sizing Calculator
Size a soft starter for LV AC induction motors with six derating factors per IEC 60947-4-2 and NEC Article 430. Evaluate rated current, AC-53a duty code, and inside-delta connection adequacy.
Smart Grid Peak Shaving Calculator
Size a Battery Energy Storage System (BESS) for peak shaving. Calculate BESS power rating, energy capacity, inverter rating, and recommended battery chemistry. Evaluate demand charge savings and simple payback period with STANDARD, LONG-DURATION, HIGH-REDUCTION, LOW-BENEFIT, and INFEASIBLE sizing classes.
kW to kVA Calculator
Convert real power in kW to apparent power in kVA using load power factor. Screen result as LOW, NORMAL, HIGH, or VERY HIGH for generator, transformer, or UPS sizing.
kVA to kW Calculator
Convert apparent power in kVA to real power in kW using load power factor. Screen result as LOW, NORMAL, HIGH, or VERY HIGH for generator, transformer, or UPS load review.
kVA to Amps Calculator
Convert apparent power in kVA to electrical current in amperes using voltage and phase configuration. Screen result as LOW, NORMAL, HIGH, or VERY HIGH for conductor, breaker, or equipment current review.
Three-Phase Power Calculator
Calculate apparent power (kVA), real power (kW), and reactive power (kVAR) for balanced three-phase systems from line voltage, line current, and power factor. Screen real power as LOW, NORMAL, HIGH, or VERY HIGH.
Wind Turbine Power Output Calculator
Estimate wind turbine electrical power output in W from rotor diameter, wind speed, air density, power coefficient, and generator efficiency. Screen result as LOW, NORMAL, HIGH, or VERY HIGH.
Voltage Divider Calculator
Calculate output voltage and divider ratio from input voltage and two resistor values using the standard unloaded divider equation. Screen result as LOW, NORMAL, HIGH, or VERY HIGH.
Busbar Sizing for Temperature Rise Calculator
Calculate busbar cross-sectional area for temperature rise, current density, and thermal loading in Metric or Imperial units. Size copper busbars for practical panel and switchboard applications.
Motor Acceleration Time Calculator
Calculate motor acceleration time from standstill to rated speed using moment of inertia, average accelerating torque, and rated speed. Screen result as VERY FAST, NORMAL, SLOW, or VERY SLOW.
Motor Current Calculator
Calculate motor full-load current in amps from motor power (kW or hp), supply voltage, phase, efficiency, and power factor. Supports single-phase and three-phase motors. Screen result as LOW, NORMAL, HIGH, or VERY HIGH.
Motor Torque Calculator
Calculate steady-state motor shaft torque in N·m or lb-ft from motor output power (kW or hp) and operating speed (rpm). Screen result as LOW, NORMAL, HIGH, or VERY HIGH.
VFD Parameter Selection Calculator
Screen motor nameplate compatibility with VFD ratings. Calculate voltage match, current loading, base V/Hz ratio, synchronous speed, and slip. Get status from WELL MATCHED to PARAMETER MISMATCH.
Inductor Design Calculator
Estimate inductance, flux density, saturation current, flux utilization, and stored energy for a simplified magnetic-core inductor. Screen saturation margin from LARGE MARGIN to SATURATION RISK.
Inductor Energy Storage Calculator
Calculate stored magnetic energy in an inductor: W = 0.5 × L × I². Accepts inductance in H, mH, or µH. Get VERY LOW to VERY HIGH energy grading with engineering interpretation.
Inductor Reactance Calculator
Calculate ideal inductive reactance X_L = 2πfL. Supports Hz/kHz/MHz and H/mH/µH. Classifies result from VERY LOW to VERY HIGH for quick AC current opposition screening.
Lighting Circuit Voltage Drop Calculator
Estimate voltage drop, percentage drop, and load-end voltage for a single-phase lighting branch circuit. Supports copper/aluminum, mm²/AWG, and m/ft inputs. Grades result from EXCELLENT to VERY HIGH.
Lighting Level Calculator (IES)
Estimate average maintained illuminance using the lumen method. Enter total lumens, area, CU, and LLF to get lux or fc and percentage of target. Grades result from WELL BELOW TARGET to OVERLIT.
Cable Pulling Tension Calculator
Estimate cable pulling tension in lbf or N from cable weight per unit length, pull length, and friction coefficient. Screen result as LOW, NORMAL, HIGH, or VERY HIGH.
Conduit Fill Calculator (NEC)
Calculate NEC conduit fill percentage for EMT, RMC, IMC, PVC, ENT, FMC, LFMC, LFNC, HDPE, and RTRC. Check Chapter 9 Table 1 limits and find the minimum compliant trade size in Imperial and Metric.
Wire Size / Ampacity Calculator (NEC)
Apply the full NEC Article 310 four-step derating chain — base ampacity (Table 310.16), ambient temperature correction, bundling adjustment, and termination temperature limit — to size copper or aluminum conductors. Auto-size mode finds the smallest compliant wire; manual mode checks your selection.
Cable Tray Fill Calculator (NEC)
Estimate cable tray fill percentage from tray width, depth, cable count, and cable diameter. Screen result as LOW, NORMAL, HIGH, or OVERFILLED for NEC 392 oriented tray capacity review.
Cable Tray Ventilation Calculator
Estimate cable tray ventilation ratio from tray width, length, and open area. Screen result as LOW, MODERATE, GOOD, or HIGH for preliminary cable tray openness and heat-dissipation screening.
CT Burden Calculator
Estimate CT secondary burden in VA from secondary current, circuit resistance, and connected-device burden. Screen result as LOW, NORMAL, HIGH, or VERY HIGH for preliminary CT secondary-circuit review.
Cable Ampacity Calculator
Estimate cable current-carrying capacity in amperes from base ampacity, correction factor, and adjustment factor. Screen result as LOW, NORMAL, HIGH, or VERY HIGH for preliminary conductor-capacity review.
Capacitor Bank Calculator
Estimate capacitor bank size in kVAR for power factor correction from real power, starting power factor, and target power factor. Screen result as LOW, NORMAL, HIGH, or VERY HIGH for preliminary reactive-compensation review.
Capacitor Sizing for Power Factor Correction
Estimate capacitor size in kVAR for power factor correction from real power, initial power factor, and target power factor. Screen result as LOW, NORMAL, HIGH, or VERY HIGH for preliminary reactive-compensation review.
Capacitor Charge/Discharge Time Calculator
Estimate RC charge or discharge time from resistance, capacitance, and a voltage transition target. Screen result as VERY FAST, FAST, MODERATE, or SLOW for preliminary RC timing review.
Crosstalk in Cables Calculator
Estimate cable NEXT and FEXT from coupling parameters, or check measured crosstalk loss, ACR-N, and ACR-F against Cat5e, Cat6, Cat6A, and Cat8 (TIA-568.2-E / ISO IEC 11801-1) limits. Get COMPLIANT or FAIL status at your test frequency.
RC Time Constant Calculator
Calculate τ = R·C for a series RC circuit. Find 5τ settling time, peak inrush current, energy stored, bleed resistor discharge time, first-order RC cutoff frequency, and circuit status from NORMAL to HIGH-STORED-ENERGY.
RL Time Constant Calculator
Calculate τ = L/R for a series RL circuit. Find settling time, steady-state current, stored energy, back-EMF screening estimate, and circuit status from NORMAL to HIGH-STORED-ENERGY.
Ground Resistance Calculator
Estimate single vertical rod grounding resistance from soil resistivity and electrode geometry. Screen result as LOW, NORMAL, HIGH, or VERY HIGH for preliminary grounding resistance review.
Ground Ring Resistance Calculator
Estimate single circular buried ground ring resistance from soil resistivity, ring radius, and conductor diameter. Screen result as EXCELLENT, GOOD, MODERATE, HIGH, or VERY HIGH for preliminary grounding ring design review.
Harmonic Distortion Calculator
Estimate Total Harmonic Distortion (THD) from the fundamental RMS value and harmonic RMS components. Screen result as EXCELLENT, GOOD, MODERATE, HIGH, or SEVERE for voltage or current waveform power quality review.
Harmonic Filter Design Calculator
Estimate the tuning frequency of a passive single-tuned LC harmonic filter from inductance, capacitance, fundamental frequency, and target harmonic order. Screen result as ON TARGET, SLIGHTLY DETUNED, MODERATELY DETUNED, POORLY TUNED, or MISTUNED.
Lightning Protection Zone Calculator – Rolling Sphere Method
Check whether a point lies inside the simplified direct-strike protection zone of a single vertical air terminal using the rolling-sphere method. Supports LPS Class I–IV, metric and imperial inputs. Grades result as WELL INSIDE ZONE, INSIDE ZONE, EDGE OF ZONE, or OUTSIDE ZONE.
Transformer Sizing Calculator
Estimate required transformer kVA from voltage, current, phase type, and design margin. Select the next standard size (5–2500 kVA) and screen utilization as VERY TIGHT, ADEQUATE, COMFORTABLE, LIGHTLY LOADED, or OVERSIZED.
Demand Factor Calculator (NEC)
Apply an NEC-style demand factor to connected load in VA or kVA. Calculate demand load, load reduction, and reduction percentage. Screen result as HEAVY REDUCTION, MODERATE REDUCTION, LIMITED REDUCTION, LOW REDUCTION, or NO REDUCTION.
Demand Response Load Shedding Calculator
Check whether available shed load is enough to meet a demand response target. Get required shedding, shed margin, coverage ratio, and post-shed demand. Screen result from MAJOR SHORTFALL to HIGH FLEXIBILITY.
Power Factor Calculator
Calculate power factor from real power and apparent power (W, kW, or MW). Get power factor decimal, percentage, reactive power share indicator, and status from VERY LOW to EXCELLENT.
Power Loss Calculator
Calculate total power loss, loss percentage, and efficiency from input and output power (W, kW, or MW). Get status from VERY LOW LOSS to VERY HIGH LOSS for first-pass electrical screening.
Power Quality Analyzer Fit Tool
Estimate whether a selected power quality analyzer profile fits the job: site voltage, current, phases, harmonic class, event capture, and recording depth. Get fit %, headroom scores, and status from UNDERSIZED to STRONGLY MATCHED.
Signal Propagation Delay Calculator
Calculate one-way signal propagation delay from path length and propagation velocity. Enter distance in m, km, ft, or mi and speed as m/s or fraction of c. Get delay in ns, µs, ms, and status from VERY SHORT to VERY LONG.
Single-Phase Power Calculator
Calculate single-phase apparent power (kVA), real power (kW), and reactive power magnitude (kVAR) from voltage, current, and power factor. Get PF status from VERY LOW PF to EXCELLENT PF for instant load efficiency screening.
Series/Parallel Resistor Calculator
Calculate equivalent resistance for series or parallel networks, match to E12/E24/E96 standards, propagate tolerance worst-case and RSS, and check per-resistor power dissipation.
Resistor Color Code Calculator
Decode 4/5/6-band resistor color codes to resistance, tolerance, and TC per IEC 60062. Encode target resistance to color band sequence with E-series (E12/E24/E96) matching.
Ohm's Law Calculator
Solve voltage, current, resistance or power from any two inputs using Ohm's Law. Supports all six input pairs with mV/kV, µA/mA, kΩ/MΩ, mW/kW prefixes. Get status from LOW-SIGNAL to HIGH-VOLTAGE for instant circuit context.
Current Divider Calculator
Calculate branch currents in parallel resistive and impedance networks. Supports 2–8 branches with R, L, C components in AC or DC mode. Get per-branch current, share, power, and RIS status (NORMAL / OVERLOADED-BRANCH).
Data Center PUE Calculator
Calculate data center Power Usage Effectiveness (PUE) in three modes: direct power snapshot, energy over a period, or component build-up. Get DCiE, overhead ratio, efficiency regime (EXCELLENT to VERY-POOR), subsystem breakdown, and a gap to a target PUE.
Op-Amp Gain Calculator
Calculate op-amp gain from resistor values for inverting, non-inverting, voltage follower, difference, and summing topologies. Get Av, dB, noise gain, and GBW-limited bandwidth.
Op-Amp Inverting/Non-Inverting Calculator
Precision design screening for inverting and non-inverting op-amp stages. Computes gain, noise gain, bandwidth, bias compensation resistor Rb, output offset from Vos and Ib, and gain error budget with A_OL screening.
Switchgear Short Circuit Rating Calculator
Calculate prospective short-circuit current (Isc) and peak fault current (ip) from transformer kVA and impedance. Verify switchgear SCCR adequacy and get NEC/IEC-compliant panel board recommendations.
Surge Protection Device Rating Calculator
Select the right SPD Type by installation location, calculate minimum MCOV from system voltage and grounding configuration, and check whether the device SCCR meets available fault current per NEC 230.67, 242, and 285.7.
Relay Coordination Calculator — IEEE C37.112 / IEC 60255-151 CTI
Calculate relay operating times and coordination time interval (CTI) per IEEE C37.112 or IEC 60255-151. Verify selectivity, detect curve crossing, and get TDS adjustment targets with practical settings for overcurrent relay coordination studies.
Inverter Sizing Calculator — Solar, Off-Grid & ILR
Size your inverter or evaluate a selected model — continuous AC capacity, surge handling, VA at low power factor, altitude/temperature derating, and DC:AC ratio (ILR) for grid-tied, off-grid, hybrid, and battery storage systems.
LED Current Limiting Resistor Calculator
Calculate the current-limiting resistor for LEDs from 3.3V, 5V, 9V, 12V, or 24V DC. Get E-series resistor value, wattage rating, actual LED current, circuit efficiency, and SAFE/INFEASIBLE/HIGH-DISSIPATION status for single and multi-LED configurations.
Radar Range Equation Calculator
Calculate radar maximum detection range, SNR, EIRP, and MDS for monostatic or bistatic pulsed radar systems. Supports IEEE 521 bands L–W, pulse integration, atmospheric loss, radio horizon, and design verification with deficit analysis.
PCB Trace Width Calculator — IPC-2221 Current Capacity by Layer
Calculate minimum PCB trace width for any current using the IPC-2221 standard. Supports external and internal layers, copper weights 0.5–4 oz, and reverse current-from-width and verify-existing modes.
PT Ratio Selection Calculator — Potential Transformer Ratio & Burden
Select the optimal potential transformer (PT) ratio for metering and protection. Calculates turns ratio, burden in VA, accuracy class per IEEE C57.13 / IEC 61869-3, and provides pass/fail analysis for VA, accuracy, and insulation class.
Panel Schedule Load Calculator — NEC Article 220 Service Sizing
Calculate electrical panel load per NEC Article 220. Supports service-sizing and verify-existing modes for residential, commercial, and industrial occupancies. Outputs code-minimum and headroom-friendly panel recommendations with soft-check advisories.
Fuse Size Calculator — NEC 240.6 / 430.52
Size overcurrent fuses per NEC 240.6(A) standard ratings for general branch circuits (NEC 210.20/240.4) and motor branch circuits (NEC 430.52). Supports time-delay and non-time-delay fuses, conductor protection checks, and Exception 2 motor startup sizing.
Fiber Optic Loss Budget Calculator — Link Power Margin
Calculate fiber optic link power margin in dB by summing fiber, connector, splice, and splitter loss against the available power budget. Get pass/fail status, dominant loss contributor, receiver overload check, and maximum supported fiber distance for multimode, singlemode, and PON links.
Expanding Categories
These engineering disciplines are in development. New calculators will be added regularly.
How to Use This Directory
- Select the category that matches your engineering task.
- Review the calculators listed under that category.
- Open the tool that best matches your required calculation.
- Enter values using the supported unit system where applicable.
- Use the result as a structured engineering estimate and verify final decisions against codes, standards, manufacturer data, and project conditions.
Frequently Asked Questions
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This page is a complete directory of all engineering calculators currently available on CalcEngineer.
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