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.