Ohm’s Law Calculator

Calculate the voltage, resistance or current of a circuit or component with the Ohm’s Law Calculator, and learn how with the integrated live example

The formula to calculate voltage is:


The formula to calculate resistance is:


The formula to calculate current is:


V = Voltage in volts
R = Resistance in ohms
I = Current in amperes

Example 1: Find the voltage across a component when the current is 2.6 amperes and the resistance is 50 ohms

V=2.6\times 50=130\; volts

Example 2: Find the resistance of a component when the voltage is 30 volts and the current is 1.3 amperes

R=\frac{30}{1.3}=23\; ohms

Example 3: Find the current through a component when the voltage is 12 volts and the resistance is 15 ohms

I=\frac{12}{15}=0.8\; amperes

Enter the Resistance and Current

How To Calculate Ohm’s Law

Enter some values to get started!

Using the Ohm’s Law Calculator

Select the value that you want to calculate and enter your figures

How To Calculate Ohm’s Law: This feature displays a live example of how to perform the selected calculation using the figures that you enter

The result is calculated and updated automatically as you enter different numbers or change between the input fields. If the calculated result hasn’t updated after you’ve finished entering your values, click or tap on the result.

Reference: ARRL – The Radio Amateur’s Handbook