Resistor Color Code Calculator
Decode a resistor's colour bands into its resistance value, and back.
Reading the coloured stripes
Resistors carry their value as coloured bands rather than printed numbers, using a code where each colour is a digit or a multiplier. Reading it from memory is error-prone, especially since the bands are small and the colours can be hard to tell apart. This decodes the bands into a resistance value and works the other way from a value to its bands.
Select the band colours to read the value, or enter a value to see the bands.
The details that cause mistakes
Two things trip people up. First, direction — the bands are read from one end, and reading a resistor backwards gives a completely wrong value, so knowing which end to start from matters. Second, the number of bands: four-band resistors are common, but five- and six-band types add precision and a temperature figure, changing how the code is read. There is also a tolerance band showing how close to the stated value the real resistance is.
Frequently asked questions
Why is reading direction important?
Because the bands are read from a specific end — reading a resistor backwards gives an entirely wrong value.
Do all resistors have the same number of bands?
No — four-band is common, but five- and six-band types add precision and a temperature coefficient, changing how the code reads.
Is anything uploaded?
No. The decoding happens in your browser.