What is Ohm’s law?
Ohm’s law describes the relationship between voltage, current and resistance in a simple electrical circuit.
Voltage = Current × Resistance
Common Ohm’s law formulas
Current can be calculated as voltage divided by resistance, while resistance can be calculated as voltage divided by current.
I = V ÷ R | R = V ÷ I
Frequently asked questions
What does V = I × R mean?
Voltage equals current multiplied by resistance.
How is power calculated?
Power in watts equals voltage multiplied by current.
Can I leave one field blank?
Yes. Enter any two of voltage, current and resistance and the calculator derives the third.