Ohm's Law Calculator (Extended)
V = IR, P = IV = I²R = V²/R. Pick which two values you know and solve for the others.
Result
How to use this calculator
- Pick which value you want to find.
- Enter the two known quantities.
- Read the result.
About this calculator
Ohm's law (V = IR) is the foundational electrical equation. Combined with P = IV, you can express any of voltage, current, resistance, or power in terms of any two of the others. The classic "wheel" of formulas: V = IR, V = P/I, V = √(PR); I = V/R, I = P/V, I = √(P/R); R = V/I, R = V²/P, R = P/I²; P = IV, P = I²R, P = V²/R.
Frequently asked
What are the units?+
Why are there 12 formulas in the wheel?+
Does Ohm's law work for AC?+
When does Ohm's law not apply?+
How is power calculated?+
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