Resistor Color Code Calculator

Read a 4-band resistor value from its colour bands.

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Resistor Color Code Calculator

How to use this tool

  1. Pick the colour of each of the four bands, in order.
  2. Press Generate to see the resistance and its tolerance range.
  3. Compare the range with the value you measure before using the resistor.

Worked example

Brown, black, red and gold mean digits 1 and 0 with a multiplier of 100, so 10 x 100 = 1000 ohms, and gold means a tolerance of 5%, giving a range of 950 to 1050 ohms.

What this tool does not do / Limits

This reads standard 4-band colour codes only and gives an estimate, not a substitute for the manufacturer's datasheet. Five- and six-band resistors, and resistors whose bands are faded or misread, are outside this tool.

Frequently asked questions

What does the gold band mean?

Gold as the fourth band means a tolerance of 5%, so the true resistance may be up to 5% above or below the stated value.

Why do two resistors with the same code measure differently?

Both can sit anywhere inside the same tolerance range, so two 1000-ohm resistors at 5% may measure 960 and 1040 ohms and both still be in specification.

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