How does a 4-band resistor code work?

The first two bands are significant digits, the third band is a multiplier (a power of ten), and the fourth band is tolerance. For example brown-black-red-gold is 10 × 100 = 1000 Ω, ±5%.

What do gold and silver mean?

As multipliers, gold means ×0.1 and silver means ×0.01. As tolerance bands, gold is ±5% and silver is ±10%.

Is anything uploaded?

No — all decoding happens locally in your browser, nothing is sent anywhere.

Resistor Color Code Calculator

Decode 4-band resistor colour bands to ohms.

Resistor colour code calculator

Through-hole resistors print their value as coloured bands. In the common 4-band scheme the first two bands are significant digits, the third is a ×10 multiplier, and the fourth is tolerance.

Select the colour of each band and the resistance — in ohms, kΩ or MΩ — plus its tolerance appears instantly, all computed in your browser.