Resistor Color Code Calculator Online

Convert resistor color bands to resistance and tolerance, or the other way around, right in your browser.

The Resistor Color Code Calculator runs entirely in your browser. The band colors and resistance values you enter never leave your device and are not uploaded to ArrayKit.

Built and maintained by Udit Agarwal

Open the Ohm's Law Calculator

About Resistor Color Code Calculator

The Resistor Color Code Calculator converts 4-band and 5-band resistor color codes into resistance and tolerance, and works the other way too: enter a resistance and it generates the matching band colors. Pick each band's color from a dropdown to decode a resistor you are holding, or type an ohm value to see which colors to look for on the part you need. It shows the resistance formatted with the right unit prefix (Ω, kΩ, MΩ), the tolerance percentage, and the full min/max range the tolerance allows. Handy for students learning the color code, hobbyists sorting a parts bin, and anyone building or repairing a circuit. Everything runs locally in your browser — no component values are uploaded.

Features

• Decode 4-band and 5-band resistor color codes into resistance and tolerance
• Encode any resistance value back into the matching color bands
• Dropdown color selectors with a live swatch next to each band
• Automatic unit formatting: Ω, kΩ, MΩ and GΩ
• Shows the tolerance range (minimum and maximum resistance)
• Supports gold and silver multiplier bands for sub-10 Ω values
• Copy the decoded value or the generated band sequence as text
• Runs entirely in your browser with nothing uploaded

How to use the Resistor Color Code Calculator

1. Choose 4-band or 5-band to match your resistor
2. Select Bands → Resistance and pick each band's color
3. Read the resistance, tolerance, and min/max range
4. Or switch to Resistance → Bands and type an ohm value to see the colors

Example

Input

brown black red gold

Output

1 kΩ ±5%

Brown-black-red-gold is a 1 kΩ resistor with 5% tolerance.

Common errors & troubleshooting

• The decoded resistance looks 10x too big or too small. — Double-check the multiplier band (the third band on a 4-band resistor) — it is easy to confuse with a digit band, especially red vs. orange or brown vs. black.
• Not sure which end of the resistor to start reading from. — The tolerance band (usually gold or silver) sits alone with extra space before it — read from the opposite end, starting with the significant digit bands.
• Resistance → Bands gives colors that don't match a resistor I bought. — Manufactured resistors only come in standard E-series values; the calculator rounds your input to the closest representable band combination, which may differ slightly from a non-standard value you typed.
• Entered a resistance and got no bands. — Enter a resistance greater than 0 — the Resistance → Bands mode needs a positive ohm value to generate a color code.

Frequently asked questions

What does the Resistor Color Code Calculator do?

It reads a resistor's color bands and calculates its resistance and tolerance, and it also works in reverse — enter a resistance and it generates the color bands you'd expect to see on that resistor.

How many bands does the Resistor Color Code Calculator support?

Both common formats: 4-band (two digits, a multiplier, and tolerance) and 5-band (three digits, a multiplier, and tolerance) resistors.

What does the tolerance band on a resistor mean?

It tells you how far the actual resistance can vary from the printed value — for example a gold band means ±5%. The calculator shows the resulting minimum and maximum resistance for that range.

Can the resistor calculator generate bands for a resistance I choose?

Yes. Switch to Resistance → Bands, type an ohm value, and it returns the digit, multiplier, and tolerance colors for a 4-band or 5-band resistor at that value.

Is the resistor color code result exact?

It is a quick estimate based on the standard color code, not a measurement. Verify the actual resistance with a multimeter before relying on it in a circuit.

Does the Resistor Color Code Calculator upload the values I enter?

No. All decoding and encoding happens locally in your browser — the colors and resistance values you work with are never sent anywhere.

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Guides

• Ohm's Law and Electrical Power, Explained

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