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Resistor Color Code Calculator

Decode or generate supported four- and five-band resistor codes with nominal resistance and tolerance.

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How this works

The tool runs in this browser. Your file or text is not uploaded to UseFreeTools. Check this tool's limits for anything it may save on your device.

Privacy details

Showing an example. Edit to see your own.

What do you want to do?
Number of bands

Used by Find the bands. A value that no four or five band code can hold exactly is refused, with the nearest coded value named.

Processed in your browser. Your inputs stay on this device.

How to use Resistor Color Code Calculator

  1. Choose decode or encode and the supported band count.
  2. Enter the ordered band colors, or a representable resistance and tolerance.
  3. Calculate and read the named band roles and nominal range.

Example: Resistor Color Code Calculator

Resistor Color Code Calculator: Brown, black, red, gold: 1000 ohm ±5%, from 950 ohm to 1050 ohm.

You add
What do you want to do?: decode Number of bands: 4 First band: brown Second band: black Third band (five band only): black Multiplier band: red Tolerance band: gold Resistance to encode (ohm): 470
You get
Brown, black, red, gold: 1000 ohm ±5%, from 950 ohm to 1050 ohm. Bands: 4 Band 1: brown (1) Band 2: black (0) Multiplier: red (×100) Tolerance: gold (±5%) Resistance = 1000 ohm Tolerance = ±5% Range = 950 ohm to 1050 ohm Bands | 4 Colour code | Brown, black, red, gold Significant digits | 1 and 0

Options

Band count
Choose the supported band arrangement before entering colors. Band positions change which colors represent digits, multiplier or tolerance.
Tolerance
The displayed interval follows the color-code tolerance around nominal resistance. It is not a measurement of the actual component.

Supported inputs and limits

Four- and five-band nominal resistance codes only. No image recognition, six-band temperature coefficient, military reliability code or power rating. Encoding refuses values the chosen digit count cannot represent exactly. Encoding accepts 0.01 to 10¹² ohms, with exact representation in the selected band count. Enter plain decimals with at most 60 characters, 40 digits and 20 fractional places per number; exponent notation is not accepted.

Where your input is processed

This tool processes your input in this browser. Your text and files are not uploaded to UseFreeTools. Check this tool's limits for anything it may save on your device.

Read the physical orientation before selecting colors

Use the separation and markings on the component to identify its reading direction. A mistaken direction or band count changes the decoded value. The page interprets selected colors; it does not inspect a photograph or determine whether a resistor is suitable for a circuit.

Questions about Resistor Color Code Calculator

Which end should I start reading from?

Use the component’s spacing and datasheet to identify the first significant digit and tolerance band. This page uses the order you enter.

Can it round my resistance to a nearby color code?

Encoding requires an exactly representable value. It does not choose a nearby preferred-series resistor for you.

Do the bands tell me the power rating?

These supported bands describe nominal resistance and tolerance. Check the component specification for power and other ratings.

Project manager: Tony Hines · Content updated 4 October 2026 · Report a problem

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