What does this tool do?
Resistor Color Code instantly calculates a resistor's value and tolerance from the color bands you select. As you click the colors it shows the result in Ω, kΩ, MΩ, or GΩ, making it a handy reference for electronics students, hobbyists, and anyone repairing circuits.
How to use it
- Enter your values into the fields.
- The result is calculated instantly.
- Read or copy the result.
4-band and 5-band resistors
The tool supports both 4-band and 5-band resistors. In 4-band mode the first two bands are digits, the third is the multiplier, and the fourth is the tolerance. In 5-band mode three significant digits are used, allowing you to read more precise resistors. When you pick the correct color for each band from the palette, the resistor preview and the calculated value update instantly, so you can match the colors on a physical resistor exactly.
How the color code works
In the standard code each color maps to a digit: black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, grey 8, white 9. The multiplier band scales the value by powers of ten, while gold and silver scale it down by 0.1 and 0.01. The tolerance band shows how far the value may deviate, for example gold means ±5% and silver means ±10%. You can copy the calculated result with a single click.
Frequently asked questions
What is the difference between a 4-band and a 5-band resistor?
4-band resistors have two significant digits, a multiplier, and a tolerance band. 5-band resistors add a third significant digit, allowing more precise values, and are typically used in precision circuits.
What do the gold and silver bands mean?
In the multiplier position, gold multiplies by 0.1 and silver by 0.01, used for sub-ohm values. In the tolerance position, gold indicates ±5% and silver indicates ±10%.
What does the tolerance percentage tell me?
Tolerance shows how much the real resistance may deviate from the calculated value. For example, a 100Ω resistor with ±5% tolerance can measure anywhere between 95Ω and 105Ω.
Is Resistor Color Code free?
Yes. Resistor Color Code and all 300+ tools on MagmaNex are completely free with no signup or account required.
Is my data safe?
Yes. Everything runs locally in your browser. The data you enter is never sent to a server, stored, or shared.
Does it work on mobile?
Yes. Resistor Color Code works on phones, tablets and desktops — no app download needed.
🔒 Privacy: everything runs in your browser, your data is never sent to a server.