Resistor Color Code Calculator (4, 5 and 6 Band)

How to read a resistor colour code

Small resistors carry coloured bands instead of printed numbers. Each colour stands for a digit: black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, grey 8, white 9. The code is defined in IEC 60062.

4 band resistors

The first two bands are digits, the third is the multiplier and the fourth is the tolerance.

R = (10 × digit 1 + digit 2) × multiplier

In the multiplier band the colour gives the power of ten: red is 100, orange is 1000. Gold means 0.1 and silver 0.01. In the tolerance band gold is 5 percent and silver 10 percent.

5 and 6 band resistors

Precision resistors have three digit bands, then the multiplier and the tolerance. Brown is 1 percent, red 2 percent, green 0.5 percent, blue 0.25 percent and violet 0.1 percent. A sixth band gives the temperature coefficient in ppm/K.

Example

Yellow, violet, red, gold: digits 4 and 7, multiplier 100. The value is 47 × 100 = 4700 Ω, or 4.7 kΩ. With 5 percent tolerance the real value lies between 4465 Ω and 4935 Ω.

Which end to start from

The tolerance band sits slightly apart from the others and is often wider: hold the resistor with that band on the right. A gold or silver band is never the first band. If in doubt read it both ways and see which value belongs to a standard series: the tool checks E6, E12 and E24.

Value to colours

A 4 band resistor carries two significant digits, 5 and 6 band resistors carry three. If the value you enter does not fit, the tool rounds it and says so.

Limits

The tolerance column lists only the colours on which sources agree. Colours on overheated, faded or discoloured resistors can mislead: measure with a meter when unsure. Surface mount resistors use a number code, not colour bands.