ELECTRONICS · CALCULATOR

Resistor colors from value

Free resistor colors from value: get first band digit, second band digit and multiplier exponent from resistance. The formula is shown; verify against the NEC.

Written by Chameera Sampath · Not yet reviewed by a licensed electrician. See the methodology.

US (NEC) only · NFPA 70 / NEC — locally adopted editionDefaults are US values. Verify the locally adopted NEC edition and project data.Official reference ↗

Project inputs

Measurements

Resistance

Updates as inputs change. Unit changes preserve the same physical values.

THE MATH BEHIND THE ANSWER

Method & assumptions

Normalize to two significant decimal digits

Digit palette: 0 black, 1 brown, 2 red, 3 orange, 4 yellow, 5 green, 6 blue, 7 violet, 8 gray, 9 white. Two-digit rounding; tolerance not encoded.

Results do not check every aspect of an electrical installation. The calculators follow US (NEC) practice only; a regional preset changes defaults such as voltage and units, and no result certifies NEC compliance.

Sources and validation →

Worked example

Resistance: 1,000 Ω

First band digit: 1 · Second band digit: 0 · Multiplier exponent: 2

This example uses the stated inputs; results for the entered values appear above.

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