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Resistor Color Calculator

Resistor Color Calculator

This Resistor Color Calculator allows you to enter resistor color codes to determine their Ohm-age (value), but it also works the other way around allowing you to enter the desired Ohm-age to find out what the needed color codes for the resistor should be.

I’ve had this one on all my old websites since way back in the day … but I do find myself going there often when I’m playing with electronic projects.
At some point I figured, it could use an update and it should probably get a home at Tweaking4All as well.

The updated version can now also calculate with 5 band resistors.

Resistor Color Calculator

The Resistor Color Calculator can be used for free of course and was written in JavaScript by myself around the year 1999 or 2000.

The original was based on an old cardboard sliding card my dad used to have to determine values and colors and it has been available at for years and after a little refresh I’ve posted it here as well.

Usage: Select your color or value in the dropdown lists below and the resistor and Ohm-age calculation will change automatically.

Resistor Type:   Additional:


  First Ring Second Ring Third Ring 1 Multiplier Tolerance Temperature 2 Failrate 3


Calculated Ohm-age:

4.7 Kilo Ω   (± 5 %)


First RingSecond RingThird Ring (optional)Multiplier RingTolerance RingTemperature Ring (optional)Failrate Ring (optional)


1 Modern metal film resistors use an extra band to indicate it’s value, sometimes referred to as a “5 band code”.
2 The temperature (coefficient) ring is often seen with precision resistors, indicating the resistance change caused by temperature changes.
3 The reliability (or: failrate) ring is rarely used in commercial applications, however frequently used in military applications.

Tips and Tricks

Make sure you read the colors in the right order!

Usually a resistor has either a silver or a gold band at the END.
Keep that one to the right (as seen above). You’re now looking at the proper color code order (from left to right).

Measuring Resistor

Sometimes, specially with damaged or durty equipment, color codes can be very hard to read.
I recommend using a regular multi-meter (Ohm-meter) to measure the resistance (if the resistor is not completely toast).

Note: Keep in mind to not hold your fingers on the contacts of the multi-meter testers or the leads of the resistor, otherwise you’re putting yourself in parallel with the resistor and the multi-meter will most likely indicate a faulty value!

Note: Do not try to measure resistors in-circuit, as the result will most likely be influenced by the ther components in the circuit and therefor resulting in a wrong vale …

Donation options

Donations are very much appreciated, but not required. Donations will be used for web-hosting expenses, project hardware or a motivational boost (a drink or snack). Thank you very much for those have donated already! It's truly AwEsOmE to see that folks like our articles and small applications.


There are 3 comments. You can read them below.
You can post your own comments by using the form below, or reply to existing comments by using the "Reply" button.

  • Nov 8, 2014 - 5:52 AM Comment Link

    […] Details of the resistor colour code can be found here, and there is a useful calculator here. […]

  • Apr 22, 2017 - 12:16 AM - Mariel Comment Link

    I’ve liked this program very much. Are you selling this program?  I’d like to use this program on my website here in Brazil. Thank You very much. 



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