Resistor Color Code Calculator

Decode resistor color bands to find resistance values or find the color code for a specific resistance.

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1. Choose the resistor type - 4-band, 5-band, or 6-band - matching the physical resistor you are reading. 2. Select the color of each band in order from left to right using the dropdown menus. 3. View the decoded resistance value, tolerance percentage, and min/max resistance range. 4. To work in reverse, enter a target resistance value and the tool displays the matching color code. 5. Use the visual resistor diagram to verify your color band selections match the physical component.

About This Tool

Resistors use colored bands to indicate their resistance value, tolerance, and sometimes temperature coefficient. Reading these bands correctly is a fundamental skill in electronics, but it can be tricky - especially with five and six band resistors or when colors are hard to distinguish under certain lighting.

This calculator works in both directions. Enter the color bands to decode the resistance value, or type in a resistance and get the corresponding color code. It supports 4-band, 5-band, and 6-band resistor configurations, covering standard and precision resistors used in modern electronics.

The tool also displays the tolerance range, showing the minimum and maximum actual resistance you can expect from the component. This is particularly helpful when selecting resistors for precision circuits where tolerance matters.

Formula / How It Works

Resistance = (Band1 x 10 + Band2) x Multiplier (4-band) | Resistance = (Band1 x 100 + Band2 x 10 + Band3) x Multiplier (5-band)

Frequently Asked Questions

A 4-band resistor has two digit bands, one multiplier band, and one tolerance band. The first two bands give a two-digit number, the multiplier band tells you what to multiply by (a power of 10), and the fourth band indicates tolerance. For example, red-violet-orange-gold means 27 x 1000 = 27k ohms with 5% tolerance.
A 5-band resistor has three digit bands instead of two, giving an extra digit of precision. The fourth band is the multiplier and the fifth is tolerance. Five-band resistors are used for precision applications. For example, brown-black-black-brown-brown means 100 x 10 = 1k ohms with 1% tolerance.
Start reading from the end where the bands are closest together or where the first band is nearest the edge. The tolerance band (often gold or silver) is always the last band and usually has a slightly wider gap separating it from the other bands.
When used as the tolerance band (last band), gold means 5% tolerance and silver means 10%. When used as the multiplier band, gold means multiply by 0.1 and silver means multiply by 0.01. These multiplier values are used for resistances below 10 ohms.
The sixth band on a resistor indicates the temperature coefficient of resistance (TCR) in parts per million per degree Celsius (ppm/C). Common values are brown (100 ppm/C), red (50 ppm/C), and blue (10 ppm/C). This band is found on high-precision resistors.

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