Ohm's Law states that V = I × R (Voltage = Current × Resistance). For a constant resistance, doubling the voltage doubles the current. It's the foundation of electrical circuit analysis.

What units does Ohm's Law use?

Voltage in Volts (V), Current in Amperes (A), Resistance in Ohms (Ω), Power in Watts (W). P = V × I = I²R = V²/R.

Ohm's Law Calculator

Quick answer: Enter any two of voltage (V), current (A), or resistance (Ω) to solve for the others.

Apply Ohm's Law (V = IR) to solve for voltage, current, or resistance in any DC circuit. Also calculates power dissipated (P = VI). Enter any two values to find the remaining two.

Last reviewed: April 2026Report an error

Solve For

Current (A)

Resistance (Ω)

Voltage

200.00 V

voltage calculated. Power: 400.00 W.

Voltage (V)

200.00

Power (W)

400.00

How to Use This Ohm's Law Calculator

1Select what you want to solve for: voltage, current, or resistance.
2Enter the two known values.
3Read the result plus power dissipated in the circuit.

Frequently Asked Questions

: Ohm's Law states that V = I × R (Voltage = Current × Resistance). For a constant resistance, doubling the voltage doubles the current. It's the foundation of electrical circuit analysis.
: Voltage in Volts (V), Current in Amperes (A), Resistance in Ohms (Ω), Power in Watts (W). P = V × I = I²R = V²/R.

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Ohm's Law Calculator

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