ELECTRONICS · CALCULATOR

Resistor and inductor color code calculator

Free resistor and inductor color code calculator for electricians, with clear inputs, an instant result, the equation behind it and a worked example. Verify.

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

ComponentFirst bandSecond bandMultiplier band

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

THE MATH BEHIND THE ANSWER

Method & assumptions

Value = (10 × digit1 + digit2) × 10^multiplier; resistors in Ω, inductors in µH

Three value bands only. Tolerance bands and manufacturer-specific inductor markings are not decoded.

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

Component: Resistor (Ω) · First band: Brown · Second band: Black · Multiplier band: Red

Decoded value: 1,000 Ω

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

Explore the electronics branch →See the related electrical concepts →

Estimating and invoicing tool

Ampxa is developing an estimating and invoicing application for electrical contractors. The list below receives notice when it opens.