Quickly Calculate the Ohm Value from a Resistor's Color Bands

A resistor is an electrical component used in electric circuits and therefore a very common element in electronics.

To find the value of a resistor in ohms, you need to read the code of the colored bands. This tool converts the different band colors of this electrical component into ohms, a value humans can understand.

Save the results

You can save the results of your resistor calculations. Just click the Save button to record the band values and colors, as well as the obtained result.

You can export this data in CSV or PDF format, so you can keep a history of your resistor calculations.

Keyboard shortcuts

f ⇝ Save

Multiplier, Tolerance and Temperature Coefficient

Definition of the multiplier

To find the value in ohms, convert the band color code to a number, then multiply it by the multiplier.

Example: Red (2), Black (0), Red (x100) = 20 * 100 = 2000 ohms.

Definition of tolerance

The tolerance is the margin of error of the resistor's value. It is expressed as a percentage and indicates the possible variation of the actual value compared to the nominal value.

Example: If the resistor's value is 1000 ohms with a 5% tolerance, the actual value can vary between 950 ohms and 1050 ohms.

Definition of the temperature coefficient

The temperature coefficient is a measure of how the resistance varies with temperature. It is expressed in parts per million (ppm) and indicates how the resistance changes with temperature.

For example, a temperature coefficient of 100 ppm means that for each degree Celsius of temperature increase, the resistance increases by 0.01%.

How a resistor works

In an electric circuit, if the generator's voltage does not change, the greater the resistance, the lower the current.