Ohm’s Law Calculator

Calculate the voltage, resistance or current of a circuit or component with the Ohm’s Law Calculator and learn on the go 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

Using the Ohm’s Law Calculator

Select the value that you want to calculate

Selecting units: You can choose your preferred units of measurement through selecting the units cells and clicking the downwards pointing arrow to display a list of available options

Learn As You Go: This feature displays a live example of how to perform the selected calculation using the figures that you enter

Calculate the:
Enter the Resistance and Current

Reference: ARRL – The Radio Amateur’s Handbook