Resistor colour code calculator
A resistor’s value and tolerance from its 4 or 5 colour bands, or the bands for a value.
About this calculator
This resistor colour code calculator reads a resistor's value from its coloured bands. Pick the colours for a 4-band or 5-band resistor.
It can also work backwards: enter a resistance and it shows the colour bands for 4-band and 5-band resistors.
How it works
The first bands are digits, the next is a power of ten to multiply by, and the last is the tolerance. Brown, black, red, gold reads 1, 0, × 100 = 1,000 Ω, or 1 kΩ, ±5%.
Last reviewed:
Worked example
- Work out: Value from colours
- Number of bands: 4 bands
- Band 1: Brown (1)
- Band 2: Black (0)
- Multiplier band: Red (× 100)
- Tolerance band: Gold (±5%)
Resistance: 1 kΩ ±5%
Common questions
How do I read a resistor colour code?
Hold the resistor with the tolerance band, usually gold or silver, on the right. Read the digit bands from the left, then multiply by the multiplier band.
What is the colour code for a 4.7 kΩ resistor?
Yellow, violet, red, gold on a 4-band resistor: 4, 7, × 100 = 4,700 Ω, ±5%.
What does the tolerance band mean?
How far the real value may be from the marked one. Gold is ±5%, so a 1 kΩ resistor can be anywhere from 950 to 1,050 Ω.
Sources and further reading
The story behind it
Where the idea came from: Colour bands came into use in the 1920s, when the Radio Manufacturers Association set a colour code for radio parts.
Bands can be read from any angle on a tiny part, where printed numbers would be too small. The code is now an international standard, IEC 60062.
Why you can trust this calculator
- It runs in your browser. Nothing you type into it is sent anywhere.
- The method is explained on this page, so you can check it yourself.
- Free to use, with no sign-up.
- Results are estimates, so please double-check anything important.
- Spotted a mistake? Tell us and we'll look into it.
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