Ohm's Law Calculator | Solve V=IR for Voltage, Current & Resistance

Ohm's Law states that V = I × R (Voltage = Current × Resistance). It describes how current flows through a conductor proportional to voltage and inversely proportional to resistance.

Power (measured in Watts) can be calculated as P = V × I, P = I² × R, or P = V² / R. Our calculator provides all four power formulas automatically based on your known values.

Standard units: Voltage in Volts (V), Current in Amperes (A), Resistance in Ohms (Ω), Power in Watts (W). This calculator also accepts millivolts (mV), microamps (µA), kilohms (kΩ), and milliwatts (mW) — just select the unit prefix from the dropdown.

Ohm's Law (V=IR) applies directly to DC circuits. For AC circuits, resistance becomes impedance (Z), which includes capacitive and inductive reactance. This calculator covers DC and resistive AC. Use the Power Calculator for AC phase angle and power factor analysis.

Yes! In guest mode, you can export your calculations to JSON format. Sign in is required for PDF and CSV export. Click the export button to download your results. This is perfect for record-keeping, sharing with others, or importing into other tools.

Yes! Your calculation history is automatically saved. Guest users can save up to 50 calculations per workspace locally. Sign in for free to save up to 100 calculations per workspace, with access from any device when logged in.

Absolutely! The Ohm's Law Calculator is completely free with no sign-up required. Create a free account to unlock additional features like more calculation history, multiple workspaces, and the ability to access your saved data from any device.