Resistor Color Code Calculator

Decode and encode 4-band, 5-band, 6-band, and SMD resistor markings

Switch between decode and encode modes. Decode reads color bands or SMD markings such as 472, 1001, 4R7, and 01C. Encode lets you enter a resistance value and get practical resistor markings back.

Example Results

3 examples

Decode a classic 4-band resistor

Read yellow violet red gold as a 4.7 kOhm resistor with 5% tolerance

{
  "result": {
    "formattedResistance": "4.7 kOhm",
    "tolerance": "±5%"
  }
}
View input parameters
{ "mode": "decode", "format": "4-band", "band1": "yellow", "band2": "violet", "multiplierBand": "red", "toleranceBand": "gold", "precision": 4 }

Decode a 6-band precision resistor

Read brown black black red brown red as 10 kOhm ±1% with 50 ppm/K

{
  "result": {
    "formattedResistance": "10 kOhm",
    "tolerance": "±1%",
    "temperatureCoefficientLabel": "50 ppm/K"
  }
}
View input parameters
{ "mode": "decode", "format": "6-band", "band1": "brown", "band2": "black", "band3": "black", "multiplierBand": "red", "toleranceBand": "brown", "tempcoBand": "red", "precision": 4 }

Decode a common SMD marking

Interpret 472 as a 4.7 kOhm surface-mount resistor code

{
  "result": {
    "family": "3-digit",
    "formattedResistance": "4.7 kOhm"
  }
}
View input parameters
{ "mode": "decode", "format": "smd", "smdCode": "472", "precision": 4 }

Key Facts

Category
Math, Date & Finance
Input Types
select, text, number
Output Type
json
Sample Coverage
4
API Ready
Yes

Overview

The Resistor Color Code Calculator is a dual-purpose utility designed to decode and encode resistor markings. It supports 4-band, 5-band, and 6-band color ring configurations, as well as surface-mount device (SMD) codes like 3-digit, 4-digit, and EIA-96 formats, allowing you to instantly calculate resistance values, tolerances, and temperature coefficients.

When to Use

  • •When identifying the resistance value and tolerance of a physical axial resistor using its colored bands.
  • •When reading surface-mount resistor markings like 472, 1001, or EIA-96 codes on a circuit board.
  • •When designing a circuit and needing to determine the correct color bands or SMD codes for a target resistance value.

How It Works

  • •Select the mode to either decode existing markings or encode a target resistance value.
  • •Choose the resistor format from 4-band, 5-band, 6-band, or SMD options.
  • •Specify the color bands or enter the SMD code for decoding, or input the resistance value, tolerance, and temperature coefficient for encoding.
  • •Read the calculated resistance value, tolerance percentage, and temperature coefficient, or view the generated color bands and SMD markings.

Use Cases

Identifying unknown resistors salvaged from old electronics or mixed component bins.
Verifying component values during PCB assembly and manual soldering tasks.
Generating manufacturing specifications and color code references for hardware design documentation.

Examples

1. Decoding a 4-Band Resistor

Electronics Hobbyist
Background
A hobbyist is repairing an old audio amplifier and needs to identify a resistor's value from its visible color bands.
Problem
The resistor has yellow, violet, red, and gold bands, and the hobbyist needs to know its exact resistance and tolerance.
How to Use
Set the mode to 'Decode Bands / Code' and format to '4-Band'. Select 'Yellow' for Band 1, 'Violet' for Band 2, 'Red' for the Multiplier Band, and 'Gold' for the Tolerance Band.
Example Config
mode: decode, format: 4-band, band1: yellow, band2: violet, multiplierBand: red, toleranceBand: gold
Outcome
The calculator outputs a resistance of 4.7 kOhm with a ±5% tolerance.

2. Reading SMD Markings on a PCB

Hardware QA Engineer
Background
A quality assurance engineer is inspecting a newly manufactured PCB prototype and needs to verify the value of an SMD resistor labeled '1001'.
Problem
Manually calculating the value of a 4-digit SMD code is slow and prone to errors during high-volume inspections.
How to Use
Set the mode to 'Decode Bands / Code', select 'SMD' format, and enter '1001' in the SMD Code field.
Example Config
mode: decode, format: smd, smdCode: 1001
Outcome
The tool decodes the marking to reveal a resistance value of 1 kOhm.

3. Determining Color Bands for a Custom Circuit

Electrical Engineer
Background
An engineer is designing a voltage divider circuit and requires a precise 10 kOhm resistor with a 1% tolerance and 50 ppm/K temperature coefficient.
Problem
The engineer needs to specify the exact 6-band color sequence for the bill of materials (BOM).
How to Use
Set the mode to 'Encode Resistance Value', select '6-Band' format, input '10k' in the Resistance Value field, select 'Brown (±1%)' for tolerance, and 'Red (50 ppm/K)' for temperature coefficient.
Example Config
mode: encode, format: 6-band, resistanceValue: 10k, tolerance: brown, temperatureCoefficient: red
Outcome
The tool outputs the required band sequence: Brown, Black, Black, Red, Brown, Red.

Try with Samples

markdown
Color Code Samples
Collection of color codes in various formats (Hex, RGB, HSL, named colors) for validation testing
title token color,code
sample
PDF Samples
Generated PDF samples from tools dated 2026-02-01 to 2026-02-10
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markdown
Test Pyramid Examples - Testing Strategy Guide
Comprehensive test pyramid implementation examples including unit tests, integration tests, E2E tests, test organization, and strategic testing patterns for balanced software quality assurance
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Magnet Link Samples
Sample magnet links for BitTorrent/P2P file sharing testing and validation
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markdown

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FAQ

What resistor formats does this calculator support?

It supports 4-band, 5-band, and 6-band color-coded axial resistors, as well as 3-digit, 4-digit, and EIA-96 SMD resistors.

How do I decode an SMD resistor marked with '4R7'?

Select SMD format, enter '4R7' in the SMD Code field, and the tool will decode it to 4.7 Ohms.

What is the difference between 5-band and 6-band resistors?

A 6-band resistor includes an additional sixth band indicating the temperature coefficient in ppm/K.

Can I find the color bands for a specific resistance value?

Yes, switch the mode to 'Encode Resistance Value', enter your target resistance, and select the desired tolerance.

What does the EIA-96 code format mean?

EIA-96 is a standard marking system for 1% tolerance SMD resistors using a two-digit code followed by a multiplier letter.

API Documentation

Request Endpoint

POST /en/api/tools/resistor-color-code-calculator

Request Parameters

Parameter Name Type Required Description
mode select Yes -
format select Yes -
smdStyle select No -
band1 select No -
band2 select No -
band3 select No -
multiplierBand select No -
toleranceBand select No -
tempcoBand select No -
smdCode text No -
resistanceValue text No -
tolerance select No -
temperatureCoefficient select No -
precision number No -

Response Format

{
  "key": {...},
  "metadata": {
    "key": "value"
  },
  "error": "Error message (optional)",
  "message": "Notification message (optional)"
}
JSON Data: JSON Data

AI MCP Documentation

Add this tool to your MCP server configuration: 

{
  "mcpServers": {
    "elysiatools-resistor-color-code-calculator": {
      "name": "resistor-color-code-calculator",
      "description": "Decode and encode 4-band, 5-band, 6-band, and SMD resistor markings",
      "baseUrl": "https://elysiatools.com/mcp/sse?toolId=resistor-color-code-calculator",
      "command": "",
      "args": [],
      "env": {},
      "isActive": true,
      "type": "sse"
    }
  }
}

You can chain multiple tools, e.g.: `https://elysiatools.com/mcp/sse?toolId=png-to-webp,jpg-to-webp,gif-to-webp`, max 20 tools.

If you encounter any issues, please contact us at [email protected]