ResistorColorBands Decoder: From Bands to Resistance Values
What resistor color bands represent
Resistor color bands encode a resistor’s nominal resistance, tolerance, and sometimes temperature coefficient. Most common resistors use 4, 5, or 6 bands:
- 4 bands: digit, digit, multiplier, tolerance
- 5 bands: digit, digit, digit, multiplier, tolerance
- 6 bands: digit, digit, digit, multiplier, tolerance, temperature coefficient (ppm/K)
Standard color-to-value chart
| Color | Digit | Multiplier | Tolerance | Temp. Coefficient (ppm/K) |
|---|---|---|---|---|
| Black | 0 | 10^0 | — | — |
| Brown | 1 | 10^1 | ±1% | 100 |
| Red | 2 | 10^2 | ±2% | 50 |
| Orange | 3 | 10^3 | — | 15 |
| Yellow | 4 | 10^4 | — | 25 |
| Green | 5 | 10^5 | ±0.5% | — |
| Blue | 6 | 10^6 | ±0.25% | 10 |
| Violet | 7 | 10^7 | ±0.1% | 5 |
| Gray | 8 | 10^8 | ±0.05% | — |
| White | 9 | 10^9 | — | — |
| Gold | — | 10^-1 | ±5% | — |
| Silver | — | 10^-2 | ±10% | — |
| None | — | — | ±20% | — |
Step-by-step decoding method
- Identify the number of bands (4, 5, or 6).
- Read the first digits from the first 2 (4-band) or 3 (⁄6-band) colored bands and convert to digits using the chart.
- Apply the multiplier (the band immediately after the digit bands) as a power of ten from the chart. Multiply the digit value by that factor.
- Read the tolerance band (usually the last visible colored band except for 6-band where an extra band follows). Use the tolerance column to find percentage.
- For 6-band resistors, read the final band for the temperature coefficient in ppm/K.
- Express the result using appropriate units (ohms, kiloohms, megaohms). Example unit thresholds: ≥1,000 → kΩ; ≥1,000,000 → MΩ.
Quick examples
-
4-band: Red, Violet, Yellow, Gold
- Digits: 2 (red), 7 (violet) → 27
- Multiplier: Yellow = 10^4 → 27 × 10,000 = 270,000 Ω = 270 kΩ
- Tolerance: Gold = ±5% → 270 kΩ ±5%
-
5-band: Brown, Black, Black, Red, Brown
- Digits: 1, 0, 0 → 100
- Multiplier: Red = 10^2 → 100 × 100 = 10,000 Ω = 10 kΩ
- Tolerance: Brown = ±1% → 10 kΩ ±1%
-
6-band: Green, Blue, Black, Orange, Brown, Red
- Digits: 5, 6, 0 → 560
- Multiplier: Orange = 10^3 → 560 × 1,000 = 560,000 Ω = 560 kΩ
- Tolerance: Brown = ±1%
- Temp. coeff.: Red = 50 ppm/K
Common pitfalls and tips
- Band order matters: hold the resistor so the tolerance band (often gold/silver or separated) is on the right.
- Faded or dirty bands can be misleading—use a magnifier and good lighting.
- Some manufacturers place the tolerance band offset slightly; look for a small gap at one end.
- For SMD resistors, color bands aren’t used—read the printed code.
Quick reference conversion
- Multiply by 10^3 → add “kΩ”; by 10^6 → add “MΩ”.
- Tolerance gives the resistance range: R_min = R × (1 − tol), R_max = R × (1 + tol).
Use this decoder method to read color-banded resistors reliably in circuits and prototyping.
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