Resistor Colour Code
Decode a 4-band resistor into resistance and tolerance.
Enter values
—
—
Step by step
The formula
resistance = (digit₁ digit₂) × multiplier, ± tolerance
Resistors are too small to print numbers on, so the value is encoded in coloured bands. The first two give the digits, the third scales them by a power of ten, and the fourth states how far from that value the real part may be.
All calculations run locally in your browser and update instantly as you type.
Example calculations
Common questions this calculator answers — select one to load its values.
Related calculators
Frequently asked questions
Which end do I read from?+
Start from the end where the bands are closest together. The tolerance band — usually gold or silver — sits slightly apart at the far end, so put that on the right.
What about 5-band resistors?+
Precision resistors use three digit bands, then a multiplier and tolerance. This tool decodes the common 4-band type; for 5-band, the first three bands are digits and the fourth is the multiplier.
All calculations run locally in your browser. Nothing you type is sent to a server.