Resistor Color Code Calculator
Decode a standard 4-band resistor's resistance and tolerance from its color bands.
Inputs explained
- Band 1 (first digit) — The color of the first band — the first significant digit. Example: Red (2).
- Band 2 (second digit) — The color of the second band — the second significant digit. Example: Red (2).
- Band 3 (multiplier) — The color of the third band — the power-of-ten multiplier. Example: Brown (×10).
- Band 4 (tolerance) — The color of the fourth band — the tolerance. Example: Gold (±5%).
How to use it
- Fill in the fields above — each input has a hint describing exactly what to enter
- Press Calculate to get your result instantly, right on this page
- Copy the result, save the tool to favorites, or share and embed it anywhere
Understanding the result
Example: Red-Red-Brown-Gold decodes to (2×10 + 2) × 10 = 220 Ω ±5%.
Frequently asked questions
What's the difference between a 4-band and 5-band resistor, and does this calculator handle both? This calculator decodes standard 4-band resistors (two significant digits, a multiplier, and a tolerance band); 5-band resistors add a third significant-digit band for tighter precision and would need a different decoding sequence.
What does the tolerance band actually tell me? It states the maximum percentage the resistor's actual resistance may deviate from its labeled value, so a gold band (±5%) on a 220 Ω resistor means the real resistance could be anywhere from about 209 to 231 Ω.
Is the Resistor Color Code Calculator free to use? Yes — it is completely free, with no sign-up, no download and no usage limits. You can use it as often as you need.
Is my data private? Yes. The calculation runs entirely in your browser — the values you enter are never sent to our servers, stored or shared with anyone.
What information do I need? Just the following: Band 1 (first digit), Band 2 (second digit), Band 3 (multiplier), Band 4 (tolerance). Each field includes a hint explaining exactly what to enter.
Can I use it on my phone? Yes — the tool is fully responsive and works on any device, and the same calculator is available in the EasyWorkCalcs mobile app.
Privacy
Everything you enter into the Resistor Color Code Calculator is processed entirely in your browser. Nothing is uploaded, stored or shared — your data stays on your device.