Lang
A · V · W · kW
Amps, Volts and Kilowatts Calculator
Calculate amps, volts and kilowatts for DC, single-phase or balanced three-phase AC. See formulas, a live graph and optional motor efficiency estimates.
Calculated automatically
Calculated automatically
Calculated automatically
Choose the system and the unknown quantity, then enter the other two values. Results update while you type. Changing a unit preserves the entered quantity.
Try an example:
Power
Formula and calculation
Power versus current
Electrical input powerMechanical shaft output
Voltage and power factor are held constant. When motor mode is enabled, the dashed line uses the selected efficiency.
This is a calculation aid, not a cable or breaker sizing tool. Installation design also requires local rules, load characteristics and assessment by a qualified electrician.
Which AC values should I enter?
Use RMS voltage and current. For balanced three-phase loads, enter line-to-line voltage and line current; power is the total for all three phases. PF = P/S, not motor efficiency.
DC: P = U × I
1φ: P = U × I × PF
3φ: P = √3 × U × I × PF
Motor calculation
Motor efficiency relates mechanical shaft output to electrical input: Pout = η × Pin. Estimates assume steady operation and do not include starting current.
Pout = η × Pin
Pin = Pout / η
Try an example
12 V × 10 A = 120 W = 0.12 kW
230 V × 10 A × 0.8 = 1,840 W
√3 × 400 V × 10 A × 0.8 ≈ 5,542.56 W
Electrical safety
This is a calculation aid, not a cable or breaker sizing tool. Installation design also requires local rules, load characteristics and assessment by a qualified electrician.
How to calculate
How to calculate
Choose the system and the unknown quantity, then enter the other two values. Results update while you type. Changing a unit preserves the entered quantity.
Which AC values should I enter?
Use RMS voltage and current. For balanced three-phase loads, enter line-to-line voltage and line current; power is the total for all three phases. PF = P/S, not motor efficiency.
Motor calculation
Motor efficiency relates mechanical shaft output to electrical input: Pout = η × Pin. Estimates assume steady operation and do not include starting current.
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