Electronics Simplified

Resistor Colour Code Calculator

Read a resistor's value from its coloured bands.

Value
220 Ω
Tolerance
±5%
Real value is between
209 Ω and 231 Ω

The formula

Value = (digits) × 10^(multiplier)

Black 0, Brown 1, Red 2, Orange 3, Yellow 4, Green 5, Blue 6, Violet 7, Grey 8, White 9. A gold multiplier means ÷ 10, silver ÷ 100. Hold the resistor with the gold or silver band on the right and read from the left.

Worked example: Red, Red, Brown, Gold

  1. Red = 2, Red = 2, so the digits are 22.
  2. Brown multiplier = 1 zero: 22 × 10 = 220 Ω.
  3. Gold = ±5%, so the real value is anywhere from 209 Ω to 231 Ω.

Common questions

Which end do I start reading from?

Put the gold or silver band on the right, then read left to right. On 5-band resistors the tolerance band (often brown) is usually set a little apart from the others.

Is there an easy way to remember the colours?

Follow the rainbow in the middle: black and brown (dark, 0 and 1), then red, orange, yellow, green, blue, violet (the rainbow, 2 to 7), then grey and white (8 and 9).

What is the difference between 4-band and 5-band resistors?

5-band resistors have three digits instead of two, so they can show more exact values. They are usually the more accurate ±1% kind.

My reading doesn't match the multimeter exactly. Is it broken?

Probably not. The tolerance band says how far off it may be: ±5% for gold. A 220 Ω gold-band resistor reading 216 Ω is fine.

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