Free online tool

Ohm's Law Calculator

Solve the complete V-I-R-P relationship with unit scaling and formula checks.

Enter exactly two known values. Leave the other two blank.

VoltageCurrentResistancePower

Voltage-

Current-

Resistance-

Power-

Method

Practical estimate method

Each calculator exposes the quantities, units, factors, and assumptions used to produce its result. Mixed units are normalized before calculation, and repeated rows are totaled before capacity comparisons.

Recipe, pacing, travel, energy, electrical, and HVAC results are planning aids. Actual cooking, performance, prices, equipment duty cycles, codes, building loads, and site conditions require context beyond the entered values.

Questions

Ohm's Law Calculator FAQ

Which two values can I enter?

Any two independent positive values among voltage, current, resistance, and power determine the other two for a resistive DC load.

Does Ohm law apply to AC circuits?

It applies directly to purely resistive loads using RMS values. Reactive AC circuits require impedance and phase or power-factor calculations.

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