Calculate resistance

With this resistor calculator you can easily calculate the value of your resistor. When you enter the colors of your resistor, the calculator will immediately calculate the value.

Reading resistances

Most “through hole” resistors have 4, 5 or 6 rings. Each ring has its own color, thanks to these color codes you can easily read the value. With 4 rings, the first two rings are a number from 0 to 9. The third ring is the multiplier. This multiplies the first two rings. The 4th ring is the tolerance of the resistor.
Example: You have a resistor with the following colors. Red – Orange – Brown – Gold. Red is 2, Orange is 3, Brown is X10, Gold is 5%. In that case the resistor is 230 ohms with a tolerance of 5%.
In a resistor, the first 3 rings are numbers.
In 6 Rings the first 3 rings are numbers and the last ring is PPM. PPM is the difference in temperature. PPM stands for “parts per million” It is expressed in PPM/ °C.

How do you calculate what resistance you need?

The resistance (R) can be calculated using Ohm's law (Ω). To calculate the resistance you need to know how much current (I) and voltage (U) you have. The formula for this is:
U = I x R
However, the above formula is suitable for calculating voltage. We want to know R. Therefore, the formula must be converted. The formula you need to calculate resistance is:
R = U/ I
(Resistance = Voltage/ Current)