What this resistance color calculator does
This tool converts resistor color bands into a resistance value in ohms, including tolerance and (for 6-band parts) temperature coefficient. It supports common 4-band, 5-band, and 6-band resistor standards used in electronics labs, repair work, and hobby circuits.
If you have ever looked at a tiny resistor and wondered whether it is 220 Ω, 2.2 kΩ, or 22 kΩ, this calculator removes that guesswork. Just pick the observed colors in order from left to right, and you get the nominal value and expected min/max range immediately.
How to use the calculator
- Select the resistor band count (4, 5, or 6).
- Choose each band color in order from the left side of the resistor.
- Click Calculate Resistance.
- Read the nominal value, tolerance range, and optional tempco result.
Band meaning by resistor type
- 4-band: 1st digit, 2nd digit, multiplier, tolerance
- 5-band: 1st digit, 2nd digit, 3rd digit, multiplier, tolerance
- 6-band: same as 5-band + temperature coefficient (ppm/K)
Quick reference: color code basics
Digit colors (significant figures)
- Black 0, Brown 1, Red 2, Orange 3, Yellow 4
- Green 5, Blue 6, Violet 7, Gray 8, White 9
Common multipliers and tolerances
- Multiplier: Gold ×0.1, Silver ×0.01, Black ×1, Brown ×10, Red ×100, ...
- Tolerance: Brown ±1%, Red ±2%, Green ±0.5%, Blue ±0.25%, Gold ±5%, Silver ±10%
Example calculations
Example 1: Red, Violet, Brown, Gold (4-band)
Digits are 2 and 7, multiplier is ×10. So 27 × 10 = 270 Ω with gold tolerance = ±5%. Real measured resistance may typically fall around 256.5 Ω to 283.5 Ω.
Example 2: Brown, Black, Black, Red, Brown (5-band)
Digits are 1, 0, 0 and multiplier is ×100, giving 10,000 Ω (10 kΩ) at ±1% tolerance.
Common mistakes to avoid
- Reading from the wrong side. Tolerance band is often spaced slightly apart.
- Confusing brown with red in poor lighting.
- Mixing up gold/silver as digits (they are usually multiplier or tolerance bands).
- Ignoring tolerance when checking measured values with a multimeter.
Why tolerance and temperature coefficient matter
The nominal resistance is only part of the story. Tolerance tells you the manufacturing spread at room temperature. Temperature coefficient (ppm/K) tells you how much that value drifts with heat. In precision analog circuits, voltage references, and sensor front-ends, these parameters can be just as important as the base resistance.