What is it?
The Resistor Colour Code Calculator reads the coloured bands on a resistor and tells you its value. It shows the resistance, the tolerance, and the lowest and highest real value.
Who is it for?
Electronics students, hobbyists and repair technicians reading resistors on circuit boards.
How to use it
- Choose the Number of bands (4, 5 or 6).
- Pick the colour of each band: 1st band, 2nd band, (3rd band), Multiplier band and Tolerance band.
Which end first?
Read the bands from the end that has the bands closer together. Gold or silver is always the last (tolerance) band. If you read it backwards, you usually get an impossible value.
Examples
- Brown, black, red, gold = 1, 0, ×100 = 1,000 Ω (1 kΩ) ±5%.
- Yellow, violet, orange, gold = 47 × 1,000 = 47 kΩ ±5%.
- 5-band resistors (1% tolerance) use three digit bands before the multiplier.
Tips
- Red and orange, or brown and red, look alike under yellow light. Use daylight, or check with a multimeter.
- Measure out of circuit: other parts in the circuit change the reading.
- A memory line for colours 0–9: Black, Brown, Red, Orange, Yellow, Green, Blue, Violet, Grey, White.
Worked example
Red, red, brown, gold: 22 × 10 = 220 Ω ±5%, so between 209 and 231 Ω.
Errors and how to fix them
- Impossible value: you read the bands backwards; start from the end away from gold or silver.
Open the tool: Resistor Colour Code Calculator
Still stuck?
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Questions, or an error not listed here?
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