Ohm's Law
Solve voltage, current or resistance — with power — from the other two.
Enter values
V
A
Ω
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Step by step
The formula
V = I × R; P = V × I
Ohm's law ties voltage, current and resistance together: V = I × R. Know any two and the third follows. Pairing it with P = V × I lets you check whether a component can handle the power it will dissipate, which is what stops things overheating.
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Example calculations
Common questions this calculator answers — select one to load its values.
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Frequently asked questions
Which two values do I need?+
Any two of voltage, current and resistance determine the third (V = I × R). Pick what to solve for and only the other two fields are read; power (P = V × I) is shown alongside.
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