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Resistor Calculator

Colour codes both ways, plus series and parallel values.

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Colour code reference

ColourDigitMultiplierTolerance

Resistance

—

Details

Tolerance—
Actual range—
Nearest E12—
Nearest E24—

—

Value with the usual engineering prefix

Read the bands from the end where they are closest to the edge; the tolerance band is normally gold or silver and sits alone at the far end. E12 and E24 are the preferred value series, spaced so the tolerance bands just cover the gaps between them.

Quick Tool Overview

The Resistor Calculator decodes colour bands into a value, encodes a value back into bands, and combines resistors in series or parallel — snapping results to the nearest E12 and E24 standard values you can actually buy.

What it does
Decodes colour codes and combines resistors
You give it
Colour bands, a resistance value, or several resistors
You get back
Value, tolerance, range and nearest standard value
Best for
Electronics projects and bench work
Calculators Free, unlimited use No sign-up Runs in your browser

About the Resistor Calculator

Work with resistors in three ways: decode colour bands into a value and tolerance, convert a value back into the bands that represent it, and combine several resistors in series or parallel.

The colour code is read from the band nearest the edge, with 4-band, 5-band and 6-band schemes all supported, since the extra bands add a significant digit and a temperature coefficient. The combination calculator also snaps its answer to the nearest E12 and E24 standard values, which is the practical question when a calculation produces 3,847 ohms and you need something you can actually buy.

Key features of the Resistor Calculator

Colour code both ways

Bands to value and value to bands, so you can identify a resistor or find the one you need.

4, 5 and 6 band schemes

The extra bands add a significant digit and a temperature coefficient, and both are handled.

Series and parallel

Combine any number of resistors, with the reciprocal arithmetic done for you.

Nearest standard value

E12 and E24 preferred values, because a calculated 3,847 ohms is not something you can buy.

Tolerance range shown

The actual band a nominal value implies, so a 5 percent 1 kΩ shows as 950 to 1,050 ohms.

How to use the Resistor Calculator

  1. 1

    Choose a mode

    Colour bands to value, value to colour bands, or series and parallel combination.

  2. 2

    Set the band count

    4, 5 or 6 bands. The extra bands add a digit and a temperature coefficient.

  3. 3

    Pick the colours

    Each band is a dropdown, and the decoded value updates as you go.

  4. 4

    Read the result

    Resistance, tolerance, the value range it implies, and the nearest standard value.

Frequently asked questions

On a 4-band resistor the first two bands are digits, the third is a multiplier and the fourth is tolerance. Read from the band closest to one end, with the tolerance band usually gold or silver.

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