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Ohm's Law & Power Calculator

Calculate Voltage (V), Current (I), Resistance (R), and Power (P) relationships. Enter any two values to calculate the others.

Formulas Used

Ohm's Law: V = I × R
Power (Apparent): S = V × I (VA)
Power (Active): P = V × I × PF (Watts)
Power (Reactive): Q = V × I × √(1 - PF²) (VARs)
Alternative: P = I² × R or P = V² / R

About This Calculator

This calculator uses Ohm's Law (V = I × R) to find voltage, current, and resistance relationships. Enter any two known values, and the calculator will determine the remaining values. For AC circuits, enter the power factor to calculate active power (Watts) and reactive power (VARs) in addition to apparent power (VA). For DC circuits or unity power factor AC circuits, use PF = 1.0.