Free Resistor Color Code Calculator
Convert a resistance value to 4-band colour code, or bands back to ohms.
The first two bands give digits, the third is the power of ten multiplier and the fourth is tolerance. In value mode it rounds to two significant digits and finds the bands, while in band mode it multiplies the two-digit number by the multiplier.
How to use the Resistor Color Code Calculator
- Enter your values, choosing the units you are working in.
- Read the result and the supporting numbers shown beneath it.
- Check the result against a second method or a reference table before you rely on it.
About the Resistor Color Code Calculator
Convert a resistance value to 4-band colour code, or bands back to ohms.
Quick, reliable engineering arithmetic saves time on site and in the workshop. These tools show their working so you can check the result.
Getting started with the Resistor Color Code Calculator
Using the resistor color code calculator takes a minute or two. Your entries are saved in this browser, so you can come back later and carry on.
Tips for better results
Hold the resistor with the tolerance band on the right to read it. Measure with a multimeter if bands are faded, since 5-band precision resistors use a different layout.
Keep units consistent from start to finish.
These tools are for estimates. Safety critical designs need a qualified engineer.
Privacy and where your data goes
Everything you type into the resistor color code calculator stays on your own device. Zapxa does not receive your numbers or documents. If you clear your browser data, your saved entries will be removed, so download a PDF of anything you want to keep.
Frequently asked questions
What does the gold band mean?
On the fourth band gold means a tolerance of 5 percent. On the third band it is a multiplier of 0.1.
Why does my value show 'nearest'?
A 4-band code stores only two digits, so values like 4.75 kΩ round to the nearest two-digit value.
Is the resistor color code calculator free?
Yes. It is free to use with no signup, no watermark and no usage limits.
Is my data private?
Yes. Your inputs are processed in your browser and saved only in its local storage. They are not uploaded to our servers.
Does it work on mobile?
Yes. Zapxa works on phones, tablets and desktops. Use the print button or download a PDF to keep a copy.
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