Power & Energy
Power Calculator
Calculate electrical power in watts and energy consumption in Wh and kWh. Enter any combination of voltage, current, or resistance — plus optional run-time for energy totals.
Power & Energy Calculator
Enter any two of V, I, R. Add time (hours) to calculate energy consumed.
Volts
Amps
Ohms (Ω)
Hours — for energy calculation
Power
—
Energy (Wh)
—
Energy (kWh)
—
Power Triangle Formulas
From Voltage + Current:
P = V × I
From Voltage + Resistance:
P = V² / R
From Current + Resistance:
P = I² × R
Energy:
Energy (Wh) = P (W) × time (hours)
Energy (kWh) = P (W) × time (hours) / 1000
Example — 12V motor drawing 3A for 2 hours:
P = 12 × 3 = 36 W
Energy = 36 × 2 = 72 Wh = 0.072 kWh
P = V × I
From Voltage + Resistance:
P = V² / R
From Current + Resistance:
P = I² × R
Energy:
Energy (Wh) = P (W) × time (hours)
Energy (kWh) = P (W) × time (hours) / 1000
Example — 12V motor drawing 3A for 2 hours:
P = 12 × 3 = 36 W
Energy = 36 × 2 = 72 Wh = 0.072 kWh