Resistor Color Code Calculator

Decode 4-, 5-, and 6-band resistor color codes into resistance, tolerance, and temperature coefficient — or read the bands for a value. Calculates in your browser.

Resistance

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Tolerance-
Minimum-
Maximum-

Show the math

The first bands are significant digits, the next is a power-of-ten multiplier, and the last is the tolerance:

R = (digits) × multiplier ± tolerance

A 4-band code uses two digit bands; a 5-band code uses three. Everything is computed in your browser.

What this does

A resistor color code calculator decodes 4-, 5-, and 6-band resistor colors into resistance, tolerance, and temperature coefficient — or reads the bands for a value.

How to use it

  1. Pick the number of bands.
  2. Select each band color.
  3. Read the resistance and tolerance.
  4. Or enter a value to get the bands.

How it works

The first bands are significant digits, the next is a power-of-ten multiplier, and the last band(s) give tolerance and (on 6-band parts) temperature coefficient.

value = significant digits × 10^multiplier

Understanding your result

The decoded value comes with a tolerance band, and that tolerance is the point: a 1,000 ohm part at 5 percent is anywhere from 950 to 1,050 ohms, so design around the range, not the nominal. Real resistors also drift with temperature and age, so for anything precision-critical pick a tighter tolerance rather than assuming the printed value is exact.

Example

Brown-black-red-gold is 1,000 Ω ±5%.

Sources & methodology

Last updated .

Frequently asked questions

How do resistor color bands work?

The first bands are significant digits, the next is a power-of-ten multiplier, and the last band(s) give tolerance and (on 6-band parts) temperature coefficient.

What does the tolerance band mean?

It is how far the real resistance may stray from the marked value — e.g. a gold band is ±5%, so a 100 Ω resistor measures 95–105 Ω.

Is my data stored?

No. Everything is calculated locally in your browser.