Electronics

Resistor Color Code Calculator

Decode a standard 4-band resistor into ohms, kilo-ohms, mega-ohms and tolerance.

Reading resistor bands

The tolerance band is usually separated from the digit and multiplier bands. If the colors are hard to read, measure the resistor with a multimeter.

Example

Brown, black, red and gold means 10 x 100 = 1,000 ohms with +/-5% tolerance.

Common mistakes

Start reading from the end opposite the separated tolerance band. Gold and silver usually belong to multiplier or tolerance positions, not the first digit.

Limitations

This calculator covers standard 4-band resistors only. Five-band precision resistors, damaged bands and in-circuit readings need extra care.

Last reviewed: 2026-05-17

Before relying on this result

Use this calculator together with the formula, assumptions, limitations and examples on the page. If the topic involves health, tax, lending, investment, legal, safety or current-rate decisions, treat the number as an estimate and check the relevant primary source or professional guidance.

Calculator metadata last reviewed: 2026-05-14.