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Ohm's Law Calculator

Enter any two of voltage, current, resistance, and power to solve the complete electrical circuit using Ohm's law.

ExampleSample values — edit any field to see your result.

Results update as you type.

Resistance (R)

550.000000Ω

Estimated result

Power (P)
22.000000W
Voltage (V)
110.000000V
Current (I)
0.200000A
Formula
Using voltage and current: V = I × R and P = V × I.
Resistance (R)550.000000 Ω
Enter any two circuit values to solve voltage, current, resistance, and power. The calculator accepts common metric electrical units and converts them before solving.

Formula

V = I × R and P = V × I. Equivalent forms include I = V/R, R = V/I, P = I²R, and P = V²/R.

Examples

110 V and 0.2 A

Resistance is 110 ÷ 0.2 = 550 Ω, and power is 110 × 0.2 = 22 W.
De-energize circuits before measuring resistance. Use instruments and procedures rated for the circuit voltage and fault current.

Frequently asked questions

What is Ohm's law?
Ohm's law states V = I × R, relating voltage in volts, current in amperes, and resistance in ohms.
How is electrical power related?
Power is P = V × I. Combining this with Ohm's law gives P = I²R and P = V²/R.
Which values should I enter?
Enter exactly two of voltage, current, resistance, and power and leave the other two blank.

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