Resistor Color Code Calculator
Decode resistor color bands to find resistance in ohms and tolerance.
Supports 4-band and 5-band resistors with the full color table and E12/E24/E96 series.
Resistor color codes are a standardized system for marking resistance values, tolerance, and temperature coefficient on small resistors where printing numbers is impractical. Each colored band represents a digit, multiplier, or tolerance value. Reading color codes is a fundamental electronics skill.
Resistance value formula (4-band resistor): Resistance = (Band1 × 10 + Band2) × 10^Band3
5-band resistor formula: Resistance = (Band1 × 100 + Band2 × 10 + Band3) × 10^Band4
Where each band’s color maps to a number:
Color code table:
| Color | Digit | Multiplier | Tolerance |
|---|---|---|---|
| Black | 0 | ×1 | , |
| Brown | 1 | ×10 | ±1% |
| Red | 2 | ×100 | ±2% |
| Orange | 3 | ×1K | , |
| Yellow | 4 | ×10K | , |
| Green | 5 | ×100K | ±0.5% |
| Blue | 6 | ×1M | ±0.25% |
| Violet | 7 | ×10M | ±0.1% |
| Gray | 8 | , | ±0.05% |
| White | 9 | , | — |
| Gold | , | ×0.1 | ±5% |
| Silver | , | ×0.01 | ±10% |
Tolerance band meaning: The final band indicates how much the actual resistance may deviate from the stated value. A 1kΩ resistor with ±5% tolerance can be anywhere from 950Ω to 1,050Ω.
Worked example: 4-band resistor: Bands: Yellow, Violet, Red, Gold
- Band 1 (Yellow): 4
- Band 2 (Violet): 7
- Band 3 (Red): multiplier ×100
- Band 4 (Gold): tolerance ±5%
Resistance = (4 × 10 + 7) × 100 = 47 × 100 = 4,700 Ω = 4.7 kΩ ±5%
Actual range: 4,700 × 0.95 to 4,700 × 1.05 = 4,465 Ω to 4,935 Ω. For precision circuits, use brown-band (1%) or better resistors to keep actual resistance close to the nominal value.
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This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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