Resistor Color Code Calculator — 4/5/6 Band Decoder & Chart

Calculate

Decode: band sequence → resistance. Encode: target resistance → band sequence.

Number of color bands on the resistor body. Most through-hole resistors use 4 (commercial) or 5 (precision) bands.

E-Series override for manual grid comparison (optional).

Overview

This calculator decodes the color band sequence on a fixed resistor (4-band, 5-band, or 6-band per IEC 60062) into resistance value, tolerance, and (for 6-band) temperature coefficient. It also supports the inverse direction: given a target resistance value and tolerance grade, the calculator returns the nearest E-series value and the color band sequence that encodes it.

Three architectural features differentiate this calculator from simplified color-code lookup tools. First, bidirectional decode/encode mode — most online tools only decode; this calculator also generates the color sequence for a target resistance value, with explicit awareness that 4-band format supports only 2 significant digits while 5-band and 6-band support 3. Second, direction ambiguity detection — when a band sequence is valid in both reading directions (rare but possible with palindromic color patterns), the calculator surfaces both interpretations side-by-side rather than guessing. Third, separated decoded validity (Track A — syntactic band sequence per IEC 60062) and catalog standardness (Track B — match against E-series preferred-number grid). A resistor may have perfectly valid bands and still classify as NON-STANDARD against the grid for legitimate reasons — custom-value parts, MIL-spec specialized values, or decade-fraction resistors that exist outside the E-series mantissa positions.

Two-track status classification. Track A — Input Validity — classifies the band sequence as DECODED-VALID (syntactically readable per IEC 60062), INVALID-COLORS (any band color is invalid for its position), or AMBIGUOUS-READING (both forward and reverse directions yield valid sequences). Track B — E-Series Match — classifies the decoded value as EXACT (sits on the E-series grid within 0.1% rounding), NEAR (within the E-series nominal tolerance band), or NON-STANDARD (outside the band). Track B is suppressed when Track A is in failure mode. For encode mode, single-track Track C classifies as ENCODED-EXACT, ENCODED-NEAR, or OUT-OF-RANGE.

This calculator handles edge cases that simplified color charts overlook. The 4-band format's 2-significant-digit limit is surfaced explicitly when encoding precision values that require 3 digits. White multiplier (theoretical ×10⁹) is excluded as a misreading source — white is digit 9 only. Direction ambiguity is detected when both forward and reverse readings are syntactically valid, with both interpretations surfaced side-by-side. MIL-PRF-39008 pink multiplier (×0.001) is supported in decode by default for sub-milliohm parts.

How to Use This Calculator

  1. Select Mode — Decode (band sequence → resistance value) or Encode (target resistance → band sequence).

  2. For Decode mode: select Band Count (4, 5, or 6 bands). The form shows the corresponding number of band color selectors.

  3. Select the color of each band in physical reading order — digit bands first, then multiplier, then tolerance, then TC (6-band only). Read from the digit-band side TOWARD the tolerance-band side.

  4. For Encode mode: enter target resistance value with unit (Ω, kΩ, or MΩ). Enter target tolerance percent (required — without tolerance, the tolerance band color cannot be determined).

  5. Optionally specify the target E-series and band count. If not specified, both auto-infer from the target tolerance value.

  6. Click Calculate — decoded resistance, tolerance, E-series match, and band-by-band breakdown appear in Results.

Read direction: bands are read from the digit side TOWARD the tolerance side. The tolerance band (typically wider, often gold or silver, farther from the body) is the orientation cue — you read TOWARD it, not from it. If you get INVALID-COLORS, try reversing the band order.

Inputs & Outputs

Inputs

Required inputs (Decode mode)

  • Mode — Decode (band sequence → resistance) or Encode (target resistance → band sequence)
  • Band Count — 4, 5, or 6 — dynamically shows the corresponding band color selectors
  • Band colors (Band 1 through Band N) — Select each band color in physical reading order from the digit side toward the tolerance side

Required inputs (Encode mode)

  • Target Resistance Value — Positive number with unit (Ω, kΩ, or MΩ)
  • Target Tolerance (%) — Required — without it, the tolerance band color cannot be determined. Common grades: 5% (general), 1% (precision), 0.1% (instrumentation)

Optional inputs (Encode mode)

  • Target E-Series — E12/E24/E48/E96/E192 — auto-inferred from tolerance if not specified
  • Target Band Count — 4, 5, or 6 — auto-inferred from tolerance (4-band for ≥5%, 5-band for <5%, 6-band requires explicit selection)
  • Target TC (ppm/°C) — Required if Target Band Count = 6. Maps to TC band color per IEC 60062
  • Allow MIL-PRF-39008 pink multiplier — Enable pink ×0.001 multiplier for sub-milliohm encoding (default disabled)

Optional inputs (Decode mode, advanced)

  • E-Series Override — Override automatic E-series selection for manual grid comparison

Outputs

Always shown (Decode mode, when DECODED-VALID)

  • Decoded Resistance — Smart-display unit (Ω, kΩ, or MΩ per magnitude)
  • Tolerance — Encoded tolerance percent (manufacturer-marked grade at factory)
  • Temperature Coefficient — TC in ppm/°C — 6-band only; does not affect nominal resistance
  • E-Series Match — Nearest E-series value, E-series grade, and signed deviation percent
  • Resistance Range — Min/Max values at ±tolerance% band
  • Status badge — DECODED/EXACT, DECODED/NEAR, DECODED/NON-STANDARD, INVALID-COLORS, or AMBIGUOUS-READING

Band-by-Band Breakdown (always shown)

  • Per-band table — Band number, color, role (Digit/Multiplier/Tolerance/TC), value or factor, and IEC 60062 section reference

Always shown (Encode mode)

  • Encoded Color Band Sequence — Color bands in reading order (digit bands first, then multiplier, tolerance, TC)
  • Nearest E-Series Value — E-series value used as encoding target, with deviation from entered target
  • Status badge — ENCODED-EXACT, ENCODED-NEAR, or OUT-OF-RANGE

Formula

Decode mode — resistance calculation:

4-band (2 significant digits): R = (d₁ × 10 + d₂) × M

5-band and 6-band (3 significant digits): R = (d₁ × 100 + d₂ × 10 + d₃) × M

Where d_i are the decoded digits per band (0–9 from Black through White) and M is the multiplier factor from the multiplier band color.

Multiplier factors: Black ×10⁰ = 1, Brown ×10¹ = 10, Red ×10² = 100, Orange ×10³ = 1000, Yellow ×10⁴, Green ×10⁵, Blue ×10⁶, Violet ×10⁷, Gray ×10⁸, Gold ×10⁻¹ = 0.1, Silver ×10⁻² = 0.01, Pink ×10⁻³ = 0.001 (MIL-PRF-39008).

E-series matching:

decade = floor(log₁₀(R)) mantissa = R / 10^decade E_nearest = closest E-series mantissa × 10^decade deviation = (R − E_nearest) / E_nearest × 100%

Classification thresholds: EXACT when |deviation| < 0.1%; NEAR when deviation ≤ E-series nominal tolerance; NON-STANDARD when deviation exceeds nominal tolerance.

Which End of the Resistor Do You Read First?

Read from the digit side TOWARD the tolerance side. The tolerance band is the orientation anchor. On most general-purpose resistors, the tolerance band is gold (±5%) or silver (±10%) — and per IEC 60062, gold and silver are not valid digit colors. This makes a gold or silver band an unambiguous end marker: the gold or silver band is always the last band in reading order. Start reading from the opposite end.

Physical spacing is the secondary cue. On 4-band resistors, the gap between Band 3 (multiplier) and Band 4 (tolerance) is often slightly wider than the gaps between the digit bands. The tolerance band may also be physically wider than the digit bands on some resistor body styles.

If the tolerance band is a precision color (brown ±1%, red ±2%) rather than gold or silver, color alone no longer anchors orientation — both ends could be read from. Rely on physical spacing: the tolerance band sits slightly farther from the body center. If unsure, enter the sequence both ways. INVALID-COLORS on the first try usually means you are reading from the wrong end.

For 5-band and 6-band resistors, the same principle applies. Bands 1–3 are digit bands, Band 4 is the multiplier, Band 5 is the tolerance, Band 6 (when present) is TC. Read toward the Band 5 tolerance color.

Decoded Validity vs E-Series Grid Match (EXACT / NEAR / NON-STANDARD)

The calculator separates two independent classifications that often confuse users. Decoded validity (Track A) asks: is the band sequence syntactically valid per IEC 60062? Catalog standardness (Track B) asks: does the decoded nominal value sit on the E-series preferred-number grid for the implied tolerance class?

EXACT — the decoded value matches an E-series catalog mantissa within 0.1% rounding tolerance. Example: 4.7 kΩ decoded from yellow-violet-red-gold matches E24 mantissa 4.7 exactly.

NEAR — the decoded value falls within the E-series nominal tolerance band but is not exactly on the grid. The value is still procurable as a standard part; verify whether the deviation is acceptable for the application.

NON-STANDARD — the decoded value is outside the E-series nominal tolerance band. The value does not sit on the preferred-number grid. Common causes: custom-value resistors, MIL-spec specialized values, decade-fraction parts between E-series mantissas, or resistors at the boundary between two adjacent mantissa cells.

These two classifications are independent. A resistor can have perfectly valid bands (Track A = DECODED-VALID) and still classify as NON-STANDARD against the grid (Track B). NON-STANDARD does NOT mean invalid, counterfeit, or out of specification.

Resistor Color Code Chart

Color Digit Multiplier Tolerance TC (6-band)
Black 0 ×1
Brown 1 ×10 ±1% 100 ppm/°C
Red 2 ×100 ±2% 50 ppm/°C
Orange 3 ×1k 15 ppm/°C
Yellow 4 ×10k 25 ppm/°C
Green 5 ×100k ±0.5% 20 ppm/°C
Blue 6 ×1M ±0.25% 10 ppm/°C
Violet 7 ×10M ±0.1% 5 ppm/°C
Gray 8 ×100M ±0.05% 1 ppm/°C
White 9
Gold ×0.1 ±5%
Silver ×0.01 ±10%
Pink ×0.001*
No Color ±20%

*Pink multiplier per MIL-PRF-39008. Decoded by default; encoded only with explicit MIL flag.

Gold and Silver Bands — Multiplier vs Tolerance

Gold and silver carry dual meanings on resistor color codes — their function depends entirely on their position in the band sequence, not on the color itself. Understanding this is essential for reading sub-ohm resistors correctly.

As tolerance bands (last position): Gold in the final band position means ±5% tolerance. Silver in the final band position means ±10% tolerance. These are the most common tolerance grades on general-purpose resistors. The gold or silver tolerance band is also the orientation anchor — it always appears at the end of the reading sequence.

As multiplier bands (Band 3 in 4-band, Band 4 in 5/6-band): Gold in the multiplier position means ×0.1. Silver in the multiplier position means ×0.01. These produce sub-ohm values. For example, Yellow-Violet-Silver-Gold decodes as (4 × 10 + 7) × 0.01 = 0.47 Ω ±5%, not 4.7 kΩ.

The position rule eliminates ambiguity: in standard IEC 60062 color coding, gold and silver are never used as digit colors (Bands 1, 2, or 3 digit positions). If you see gold or silver as the apparent first band, you are reading from the tolerance side — reverse the reading direction.

4-Band vs 5-Band vs 6-Band Resistor Color Codes

4-band (most common, general purpose): 2 digit bands + 1 multiplier band + 1 tolerance band. Encodes 2 significant digits. Typical tolerance: ±5% (gold) or ±10% (silver). E-series: E12 and E24. Use case: hobby, consumer electronics, low-precision general purpose.

5-band (precision standard): 3 digit bands + 1 multiplier band + 1 tolerance band. Encodes 3 significant digits. Typical tolerance: ±1% or tighter. E-series: E48, E96, E192. Use case: instrumentation, op-amp feedback networks, voltage references.

6-band (precision with temperature stability): 3 digit bands + 1 multiplier band + 1 tolerance band + 1 TC band. Encodes 3 significant digits plus thermal drift specification. TC range: 1 ppm/°C (gray) to 100 ppm/°C (brown). Use case: precision instrumentation requiring temperature stability.

Direction Ambiguity in Resistor Color Codes

In most resistors, the tolerance band (gold or silver) physically anchors orientation unambiguously — these colors cannot appear in digit positions. True direction ambiguity is rare. It occurs only when the band sequence is palindromic in role assignments: every color in the sequence is valid in both the digit and tolerance positions.

A canonical example is Brown-Red-Brown-Red on a 4-band resistor: forward reading gives 120 Ω ±2%, reverse reading gives 2.1 kΩ ±1%. Both readings are syntactically valid. The calculator surfaces both interpretations side-by-side. Look for the slightly wider band farther from the body — that's the tolerance side, read TOWARD it.

Encoded Tolerance vs Measured Tolerance vs Procurement Tolerance

Three distinct tolerance values appear in resistor specifications. Confusing them is a common source of specification errors and procurement mismatches.

Encoded tolerance is the grade marked on the resistor body by color band. It is set at the factory during final sorting and inspection. A gold band (±5%) means the actual resistance was within ±5% of nominal when the part was manufactured. The encoded grade is the manufacturer's declaration at time of manufacture.

Measured tolerance is the actual resistance deviation measurable today, at your bench, at a specific temperature. Actual resistance can drift from the factory-encoded grade due to aging, thermal cycling, moisture absorption, and mechanical stress. For applications where accuracy matters — precision instrumentation, voltage references, low-noise circuits — verify by ohmmeter measurement rather than relying on the encoded band.

Procurement tolerance is the tolerance specification you place in your BOM or purchase order. Procurement tolerance may be tighter than the encoded band tolerance. Modern component distributors sort and re-grade standard catalog parts — it is common practice to procure E24-series gold-band (±5% encoded) resistors tested to 1% at the distributor level, without changing the color band marking. The procurement spec governs what the supplier ships; the encoded band governs what is marked on the part. Both can be simultaneously accurate without contradiction.

This calculator decodes the encoded tolerance only — the color band grade. For procurement and measurement specifications, consult the distributor datasheet or verify by direct measurement.

Common Resistor Color Codes — Quick Reference

Value 4-band (±5% Gold) 5-band (±1% Brown)
1 Ω Brown-Black-Gold-Gold Brown-Black-Black-Silver-Brown
10 Ω Brown-Black-Black-Gold Brown-Black-Black-Gold-Brown
100 Ω Brown-Black-Brown-Gold Brown-Black-Black-Black-Brown
1 kΩ Brown-Black-Red-Gold Brown-Black-Black-Brown-Brown
4.7 kΩ Yellow-Violet-Red-Gold Yellow-Violet-Black-Brown-Brown
10 kΩ Brown-Black-Orange-Gold Brown-Black-Black-Red-Brown
47 kΩ Yellow-Violet-Orange-Gold Yellow-Violet-Black-Red-Brown
100 kΩ Brown-Black-Yellow-Gold Brown-Black-Black-Orange-Brown
1 MΩ Brown-Black-Green-Gold Brown-Black-Black-Yellow-Brown
10 MΩ Brown-Black-Blue-Gold Brown-Black-Black-Green-Brown

Key Facts

  • 4-band resistors encode 2 significant digits; 5-band and 6-band encode 3 significant digits. 4-band is the most common general-purpose format.
  • Reading direction: bands are read from the digit side TOWARD the tolerance side. The tolerance band (typically wider, often gold or silver, farther from the body) is the orientation cue.
  • Gold and silver have DUAL roles: tolerance band (gold ±5%, silver ±10%) when in the last position, or multiplier (gold ×0.1, silver ×0.01) when in the multiplier position. Position determines role.
  • E-series matching is grid classification, not validity. A resistor with decoded value not on the grid (NON-STANDARD class) is NOT invalid — it may be a custom-value, MIL-spec, or decade-fraction part.
  • Encoded tolerance is the manufacturer-marked grade at factory. Procurement tolerance (specified at order time) may be tighter — modern catalogs offer E24 values (gold band, ±5% marked) at 1% measured tolerance.
  • True direction ambiguity (both forward and reverse readings yield valid sequences) is rare. It requires a palindromic role pattern AND a tolerance band that is not gold or silver.

Applications

  • Bench identification and repair workflow — reading resistors during prototype assembly, debugging, or rework on legacy equipment
  • Verifying correct part placement on assembled PCBs during inspection or troubleshooting
  • Decoding salvaged resistors from older equipment for hobbyist reuse
  • Validating supplier shipment markings against BOM specifications during incoming inspection
  • BOM and procurement documentation — specifying color-band markings for visual quality inspection
  • Generating expected band sequences for incoming inspection checklists and production line reference cards
  • Procurement decision support — identifying whether a decoded value is a standard E-series catalog part (single-source, low cost) or a custom-value part
  • Educational use — demonstrating the E-series preferred-number system and the 4-band vs 5-band trade-off

Example Calculation

Example 1 — Standard 4-band 4.7 kΩ ±5% (EXACT E24 match)

Inputs: Decode mode, 4-band, bands = [Yellow, Violet, Red, Gold].

Band-by-band:

  • Band 1: Yellow → digit 4
  • Band 2: Violet → digit 7
  • Band 3: Red → multiplier ×100
  • Band 4: Gold → tolerance ±5%

Resistance: (4 × 10 + 7) × 100 = 47 × 100 = 4700 Ω = 4.7 kΩ

E-series match: tolerance ±5% → E24. Mantissa 4.7 is a standard E24 value. Nearest: 4.7 kΩ. Deviation 0.00%. EXACT.

Track A: DECODED-VALID. Track B: EXACT. Badge: DECODED / EXACT.


Example 2 — Standard 5-band 1.50 kΩ ±1% (EXACT E96 match)

Inputs: Decode mode, 5-band, bands = [Brown, Green, Black, Brown, Brown].

Band-by-band:

  • Band 1: Brown → digit 1
  • Band 2: Green → digit 5
  • Band 3: Black → digit 0
  • Band 4: Brown → multiplier ×10
  • Band 5: Brown → tolerance ±1%

Resistance: (1 × 100 + 5 × 10 + 0) × 10 = 150 × 10 = 1500 Ω = 1.5 kΩ

E-series match: tolerance ±1% → E96. Mantissa 1.50 is a standard E96 value. Nearest: 1.50 kΩ. Deviation 0.00%. EXACT.

Badge: DECODED / EXACT.


Example 3 — Direction ambiguity (Brown-Red-Brown-Red)

Inputs: Decode mode, 4-band, bands = [Brown, Red, Brown, Red].

Forward reading:

  • Band 1: Brown → digit 1
  • Band 2: Red → digit 2
  • Band 3: Brown → multiplier ×10
  • Band 4: Red → tolerance ±2%
  • Resistance: (1 × 10 + 2) × 10 = 120 Ω ±2%

Reverse reading:

  • Band 1: Red → digit 2
  • Band 2: Brown → digit 1
  • Band 3: Red → multiplier ×100
  • Band 4: Brown → tolerance ±1%
  • Resistance: (2 × 10 + 1) × 100 = 2.1 kΩ ±1%

Both sequences are syntactically valid per IEC 60062. The calculator surfaces both interpretations. Badge: AMBIGUOUS-READING.

To resolve: physically inspect the resistor. The tolerance band is typically slightly wider and farther from the body center. If the rightmost band (Red) is the wider one, the forward reading (120 Ω ±2%) is correct.


Example 4 — Encode mode: 4-band guardrail for tight tolerance (4.32 kΩ ±1%)

Inputs: Encode mode, target resistance = 4.32 kΩ, tolerance = 1%, target band count = 4 bands.

4.32 kΩ requires 3 significant digits. 4-band format supports only 2 significant digits. The calculator rounds to the nearest 2-digit E-series value: 4.3 kΩ (mantissa 4.3 × 10³).

Encoded sequence: Yellow-Orange-Red-Brown (4.3 kΩ ±1%).

  • Band 1: Yellow → digit 4
  • Band 2: Orange → digit 3
  • Band 3: Red → multiplier ×100
  • Band 4: Brown → tolerance ±1%

Deviation from target: (4320 − 4300) / 4300 × 100 = +0.47%. Within ±1% tolerance band. Badge: ENCODED-NEAR.

The calculator shows a guardrail note: 4-band cannot encode the full 3-digit precision of 4.32 kΩ. Use 5-band for exact encoding.


Example 5 — Sub-ohm 0.47 Ω with Silver multiplier

Inputs: Decode mode, 4-band, bands = [Yellow, Violet, Silver, Gold].

Band-by-band:

  • Band 1: Yellow → digit 4
  • Band 2: Violet → digit 7
  • Band 3: Silver → multiplier ×0.01
  • Band 4: Gold → tolerance ±5%

Resistance: (4 × 10 + 7) × 0.01 = 47 × 0.01 = 0.47 Ω

E24 nearest: 0.47 Ω (mantissa 4.7, decade 10⁻¹). Deviation 0.00%. EXACT.

Silver in Band 3 (multiplier position) means ×0.01 — fractional multiplier for sub-ohm values. This is distinct from Silver in the last band position (tolerance ±10%). Position determines role.

Badge: DECODED / EXACT.


Example 6 — Encode mode for 10 kΩ ±1%, 5-band

Inputs: Encode mode, target resistance = 10 kΩ, tolerance = 1%, band count = 5-band.

E96 (auto from 1%) → mantissa 1.00, decade 4 → E_nearest = 10 kΩ, deviation 0.00%.

Decompose 10.0 kΩ (3 digits): digits 1, 0, 0; multiplier ×100 = Red. Color sequence: Brown-Black-Black-Red-Brown (10 kΩ ±1%).

Badge: ENCODED-EXACT.

Standards & References

  • Official standards
  • IEC 60062 — Marking codes for resistors and capacitors (color code definitions, band placement, alphanumeric marking)
  • IEC 60063 — Preferred number series for resistors and capacitors (E-series E12, E24, E48, E96, E192 definitions)
  • IEC 60115 series — Fixed resistors for use in electronic equipment (general technical specifications, derating curves)
  • MIL-PRF-39008 — Resistors, fixed, composition (introduces pink multiplier ×0.001 for sub-milliohm parts). Available via Defense Logistics Agency ASSIST database
  • Practical engineering references
  • Vishay — Resistor product family with datasheets and derating guides
  • Yageo — Chip Resistor technical documentation
  • KOA Speer — Resistor products and technical resources
  • Bourns — Resistor product line and technical notes

Units

Resistance units: Results are displayed with automatic smart unit selection (Ω for < 1 kΩ, kΩ for 1 kΩ to < 1 MΩ, MΩ for ≥ 1 MΩ). Sub-ohm values (< 1 Ω) display as mΩ. Internal calculation always in Ω.

Tolerance units: Percent (%). Encoded grade = manufacturer-marked tolerance at factory. Procurement tolerance may differ.

Temperature coefficient units: ppm/°C (parts per million per degree Celsius). Affects thermal drift only; does NOT change nominal decoded resistance value.

Limitations

  • Calculator handles fixed resistors with axial leads and color bands per IEC 60062. SMT chip resistors (which use numeric codes) are out of scope — use the SMT Resistor Code Calculator.
  • 4-band, 5-band, and 6-band color codes supported. 3-band (±20% implied) and military-spec band codes with extra reliability indicator bands are out of scope.
  • Color enumeration per IEC 60062. Non-IEC color codes (Russian GOST 11151, Japanese JIS, vintage military codes) are out of scope.
  • White multiplier (×10⁹) is not supported — white is digit 9 only. White in multiplier position is almost always a misreading.
  • Pink multiplier (×0.001, MIL-PRF-39008) supported in decode by default. Supported in encode only when MIL pink flag is enabled.
  • Direction ambiguity detection flags when BOTH forward AND reverse readings are syntactically valid — calculator surfaces both interpretations but cannot determine which is correct from color data alone.
  • Calculator decodes the encoded tolerance grade, not the actual measured tolerance. Aging, thermal cycling, and environmental exposure can shift actual resistance from the marked grade.

Common Mistakes to Avoid

  • Reading from the wrong end — if you get INVALID-COLORS, the most likely cause is reading from the tolerance-band side instead of the digit-band side. Reverse the band order and re-enter.
  • Confusing gold/silver role — Gold and silver serve DUAL roles: as the LAST band they are tolerance (±5% / ±10%); in the multiplier position they indicate fractional multiplier (×0.1 / ×0.01) for sub-ohm resistors.
  • Assuming NON-STANDARD means invalid — NON-STANDARD classification means the decoded value does not sit on the E-series preferred-number grid. Custom-value, MIL-spec, and decade-fraction resistors legitimately exist outside the grid.
  • Using encoded tolerance as procurement tolerance — encoded grade (e.g. gold band ±5%) is the manufacturer-marked grade at factory. Modern catalogs offer tighter procurement tolerances on the same physical part.
  • Using 4-band encoding for precision values — 4-band supports only 2 significant digits. A 4.32 kΩ E96 target cannot be exactly encoded in 4-band format; use 5-band for precision values.

Frequently Asked Questions

How do I read a 5-band resistor?
A 5-band resistor has three digit bands (Bands 1–3), one multiplier band (Band 4), and one tolerance band (Band 5). Read in order: the first three bands give digits d₁, d₂, d₃; Band 4 gives the multiplier; Band 5 gives the tolerance grade. Resistance = (d₁ × 100 + d₂ × 10 + d₃) × multiplier. For example, Brown-Green-Black-Brown-Brown = (1 × 100 + 5 × 10 + 0) × 10 = 1500 Ω = 1.5 kΩ ±1%. The tolerance band on 5-band resistors is often brown (±1%) or red (±2%) — colors that also appear in digit positions — so reading direction is determined by physical spacing rather than color alone.
Can gold be the first band on a resistor?
No. Gold is not a valid digit color per IEC 60062 and cannot appear in Band 1 or Band 2 in standard color codes. Gold is valid only as a multiplier (×0.1, Band 3 in 4-band or Band 4 in 5/6-band) or as a tolerance indicator (±5%, last band). If you see gold or silver at the end you are currently reading from, you are reading from the wrong end — that end is the tolerance side. Reverse the resistor and start reading from the opposite end.
Why does the calculator show AMBIGUOUS-READING?
AMBIGUOUS-READING means both the forward and the reversed band sequences decode to valid resistor values per IEC 60062. The calculator cannot determine the correct orientation from color data alone. This occurs when the tolerance band color (brown, red, green, blue, violet, gray) also appears in valid digit positions, removing the orientation cue that gold or silver normally provides. To resolve: physically inspect the resistor. The tolerance band is typically slightly wider and sits farther from the body center than the digit bands. Read toward the tolerance band.
What is the difference between EXACT, NEAR, and NON-STANDARD?
These are E-series catalog match classifications (Track B). EXACT means the decoded nominal value sits on the E-series preferred-number grid within 0.1% rounding tolerance — standard catalog procurement applies directly. NEAR means the value falls within the E-series nominal tolerance band but is not precisely on the grid mantissa — still a standard catalog range. NON-STANDARD means the value is outside the E-series nominal tolerance band. NON-STANDARD does not mean the resistor is invalid — it may be a custom-value, MIL-spec, or decade-fraction part that legitimately exists outside the E-series grid.
What color code is 4.7 kΩ?
Standard 4-band ±5%: Yellow-Violet-Red-Gold (4.7 kΩ ±5%). Precision 5-band ±1%: Yellow-Violet-Black-Brown-Brown (4.70 kΩ ±1%). Yellow encodes digit 4, Violet encodes digit 7, Red is multiplier ×100. Result: 47 × 100 = 4700 Ω = 4.7 kΩ. This is a standard E24 mantissa value (mantissa 4.7), meaning it is always an EXACT match on the E24 grid.
What color code is 10 kΩ?
Standard 4-band ±5%: Brown-Black-Orange-Gold (10 kΩ ±5%). Precision 5-band ±1%: Brown-Black-Black-Red-Brown (10.0 kΩ ±1%). Brown encodes digit 1, Black encodes digit 0, Orange is multiplier ×1k (×1000). Result: 10 × 1000 = 10,000 Ω = 10 kΩ. This is a standard E12 and E24 mantissa value (mantissa 1.0), meaning it is always an EXACT match on both grids.
What does NON-STANDARD mean — is my resistor invalid?
NON-STANDARD means the decoded nominal value does not sit on the E-series preferred-number grid for the implied tolerance class. It does NOT mean the resistor is invalid, counterfeit, or out of specification. Common legitimate causes include custom-value resistors made to a specific application requirement, MIL-spec specialized values per MIL-PRF-39008, decade-fraction resistors between adjacent E-series mantissas, and parts from older manufacturer runs. If the part looks physically intact and the bands are unfaded, the marking is likely correct. Verify by ohmmeter measurement if part identity matters.
What is the difference between encoded tolerance, procurement tolerance, and measured tolerance?
Encoded tolerance is the grade the manufacturer marked on the resistor at factory (e.g. gold band = ±5%). Procurement tolerance is the tolerance you specify at purchase, which may be tighter — modern catalogs offer E24 gold-band parts sorted to 1% measured tolerance. Measured tolerance is the actual resistance deviation today, which can drift from the procurement specification due to aging, thermal cycling, and humidity exposure. The calculator decodes the encoded grade only; verify the actual resistance by ohmmeter measurement when precision matters.
Can I use this calculator for SMT chip resistors?
No. This calculator handles axial-lead through-hole resistors with color band markings per IEC 60062. SMT chip resistors use a different marking system — a 3-digit or 4-digit numeric code (for example, 103 for 10 kΩ or 1002 for 10.0 kΩ in the EIA-96 system). A dedicated SMT resistor code calculator is the correct tool for chip resistor identification. SMT chip resistors do not use color bands.
Why does the calculator not support white in the multiplier position?
White represents digit 9 only per IEC 60062 as used in this calculator. The theoretical ×10⁹ multiplier (10 GΩ range) is extremely rare in real fixed axial resistors — production of such parts uses different construction and marking methods. White appearing in a multiplier position on a bench resistor is almost always a misreading (faded gray, for example). Supporting white as a multiplier would create more user confusion from false positives than practical value.

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