Ohm's Law Calculator
Solve for voltage, current, resistance or power using Ohm's law from the values you know.
How it works
V = I · R, I = V / R, R = V / I, P = V · I
Ohm's law ties together the voltage across a component, the current through it and its resistance. Pick which quantity you want and the calculator uses the two most relevant known values to solve for it. Power is the product of voltage and current.
Worked example
A 2 A current through a 6 Ω resistor produces V = I × R = 2 × 6 = 12 V, dissipating 24 W of power.
Frequently asked questions
Which two values do I need?
To solve for voltage you need current and resistance; for current, voltage and resistance; for resistance, voltage and current; for power, voltage and current. Enter those and pick the target.
Why can resistance or current not be zero?
Dividing by zero is undefined. Zero resistance would imply infinite current for any voltage, and zero current makes the resistance calculation meaningless, so those cases are blocked.
Does Ohm's law always hold?
It holds for ohmic conductors where resistance is constant. Devices like diodes and lamps are non-ohmic, so the simple linear relationship only approximates their behaviour.
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