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Resistor Calculator | Decode Colour Bands and Combine Values

Decode resistor color bands into resistance values, and generate the band code for any resistance you need. The essential electronics reference — read 4- and 5-band resistors correctly every time.

Last updated: June 2026 · Free · No sign-up required

Results

Enter values above and click Calculate to see your result instantly.

Quick reference

Resistor color values:

ColorDigitMultiplier
Black0x1
Brown1x10
Red2x100
Orange3x1k
Yellow4x10k
Green5x100k

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Responsive design tested down to a 320px-wide phone screen. The input fields use native number/date keyboards on iOS and Android, the calculate button is thumb-sized, and the result still reads big and bold on the smallest screen. No app to download, ever.

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Interpretation guide

Tolerance bands:

ColorTolerance
Gold+/-5%
Silver+/-10%
Brown+/-1%
Red+/-2%

lightbulb Worked example

Let's say you are using the Resistor Calculator. Decodes resistor colour bands into resistance values, and solves series and parallel resistor networks. Enter the four or five colour bands and the tool returns the resistance, tolerance, and Enter the values that match your situation into the input fields and press calculate — using realistic numbers makes the result directly useful for you.

Result: The calculator instantly applies the formula 4-band: digit, digit, x multiplier, tolerance; 5-band adds a third significant digit and returns the result with appropriate precision.

What this means: Read the result in the context of what you are measuring. The step-by-step breakdown lets you confirm the math and understand which input most affects the outcome.

Formula & methodology

Formula: 4-band: digit, digit, x multiplier, tolerance; 5-band adds a third significant digit

The Resistor Calculator is built on a well-established calculation method. It uses the formula 4-band: digit, digit, x multiplier, tolerance; 5-band adds a third significant digit to turn your inputs into a reliable result. Decodes resistor colour bands into resistance values, and solves series and parallel resistor networks. Enter the four or five colour bands and the tool returns the resistance, tolerance, and temperature coefficient. The steps are shown on the page so you can follow the reasoning from input to output.

Resistor bands encode resistance and tolerance by color. In a 4-band resistor the first two bands are significant digits, the third is a power-of-ten multiplier, and the fourth is tolerance. A 5-band resistor adds a third significant digit for tighter precision. The calculator converts color bands to a resistance value (and back), so you can read or specify a resistor without a multimeter.

Authoritative source: timeanddate.com

Frequently asked questions

How do I read a 4-band resistor?
Enter the required values into the input fields and press the calculate button. The tool applies the formula 4-band: digit, digit, x multiplier, tolerance; 5-band adds a third significant digit and returns the result with a short explanation of each step, so you can check the working yourself.
What's the difference between 4-band and 5-band?
The Resistor Calculator is free, private, and accurate: it runs entirely in your browser (no uploads, no accounts), applies the standard calculation, and explains each step so you can verify the result. Decodes resistor colour bands into resistance values, and solves series and parallel resistor networks. Enter the four or five colour bands and the tool returns the resistance, tolerance, and temperature coefficient. You can also enter resistor values to find There is no limit on usage, and it works on any device.
What does the gold band mean?
The Resistor Calculator is a free online tool that decodes resistor colour bands into resistance values, and solves series and parallel resistor networks. enter the four or five colour bands and the tool returns the resistance, tolerance, and temperature coefficient. you can also enter resistor values to find. You enter a few values, and it returns an accurate result together with a step-by-step explanation, so it works as both a calculator and a quick reference for the underlying concept.
How do I read the bands in the right direction?
Hold the resistor so the tolerance band (gold, silver, or none) is on the RIGHT. Read the first two or three significant digits left to right, then the multiplier, then the tolerance. The calculator does this automatically when you select the band colors — it also handles the direction ambiguity by checking which reading is plausible.
Can I find the color code from a resistance value?
Yes — enter a resistance value like 4,700 Ω and the calculator returns the band colors (yellow, violet, red for a 4-band 4.7 kΩ, or a 5-band code for more precision). It also shows the E-series value it matches and the tolerance options, so you can identify the physical resistor you need on the shelf.
What does the Resistor Calculator do?
Decodes resistor colour bands into resistance values, and solves series and parallel resistor networks. Enter the four or five colour bands and the tool returns the resistance, tolerance, and temperature coefficient. You can also enter resistor values to find. The calculator takes your inputs, applies the standard calculation, and returns a clear result so you can make an informed decision without doing the math by hand.
What formula does the Resistor Calculator use?
The Resistor Calculator applies the standard formula: 4-band: digit, digit, x multiplier, tolerance; 5-band adds a third significant digit. The tool walks through each step of the calculation so you can verify the numbers yourself.
Is the Resistor Calculator free and private?
Yes — the Resistor Calculator. There is no sign-up, no paywall, no trial, and no limit on how many calculations you can run. CalcaTools covers its costs with non-intrusive display advertising, so the calculator itself never asks for payment or restricts any feature.
How accurate is the Resistor Calculator?
The Resistor Calculator applies the standard formula: 4-band: digit, digit, x multiplier, tolerance; 5-band adds a third significant digit. It is tested against published worked examples before launch and uses native double-precision arithmetic, so results are accurate to typical precision for the values you enter — with no intermediate rounding that could distort the answer.

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