Ohm’s Law Calculator
Solve voltage, current or resistance from the other two entered circuit values and show the corresponding V×I real-power product for a DC or unity-power-factor model.
Result
Calculated unit
Formula
Calculation logicFormula definitions and substituted values.
Calculated value
First known value (unit per selected mode) * Second known value (unit per selected mode) if Solve for = voltage; First known value (unit per selected mode) / Second known value (unit per selected mode) if Solve for = current; First known value (unit per selected mode) / Second known value (unit per selected mode) otherwise
First known value (unit per selected mode) * Second known value (unit per selected mode) if Solve for = voltage; First known value (unit per selected mode) / Second known value (unit per selected mode) if Solve for = current; First known value (unit per selected mode) / Second known value (unit per selected mode) otherwiseCalculated unit
V if Solve for = voltage; A if Solve for = current; ohm otherwise
V if Solve for = voltage; A if Solve for = current; ohm otherwiseCalculated V×I power product (W)
Calculated value * First known value (unit per selected mode) if Solve for = voltage; First known value (unit per selected mode) * Calculated value if Solve for = current; First known value (unit per selected mode) * Second known value (unit per selected mode) otherwise
Calculated value * First known value (unit per selected mode) if Solve for = voltage; First known value (unit per selected mode) * Calculated value if Solve for = current; First known value (unit per selected mode) * Second known value (unit per selected mode) otherwiseBefore relying on the result
- Find current from voltage and resistance
- Find resistance from voltage and current
- Calculate the selected missing electrical value from two known positive values.
Related calculators
Electrical Load Current Calculator
Convert electrical input power to line current, per-phase real power and apparent power for a single-phase or balanced three-phase supply.
Open calculatorFinal Subcircuit Maximum Demand Calculator
Estimate one final subcircuit demand from point counts, fixed-load contribution and explicit project factors.
Open calculatorGenerator kVA Requirement Calculator
Estimate a generator's apparent-power requirement by comparing steady demand with a largest-motor start condition and explicit project reserve.
Open calculatorLighting Load and Circuit Estimate
Estimate single-phase-equivalent lighting load, apparent load, current, and an arithmetic circuit count from user-entered luminaire input data.
Open calculator