Resistor color code calculator
A four-band resistor encodes its value in colour: two significant digits, a decimal multiplier, and a tolerance band. Select the bands in order and the value appears below.
Results
- Resistance
- —
- Tolerance
- —
- Value range
- —
Results update as you type.
Formula
R = (digit1 × 10 + digit2) × multiplier
range = R ± tolerance
How it works
Read the bands from the end where they are grouped closest together. The first two are digits, the third scales them by a power of ten, and the slightly separated fourth band is the tolerance.
Gold and silver in the multiplier position mean ×0.1 and ×0.01 — used for resistors below 10 Ω. In the tolerance position gold is ±5% and silver ±10%, the most common everyday parts.
This covers the four-band scheme; five- and six-band precision resistors add a third digit and a temperature-coefficient band, which are on the roadmap.