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Ampere to Watt Calculator

Convert amperes to watts using voltage, or watts to amperes.

Last Updated: May 5, 2026

Circuit Type

Power (Watts)

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Kilowatts

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Horsepower

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Formulas

DC: P = I × V
AC 1Φ: P = I × V × PF
AC 3Φ: P = √3 × I × V × PF
1 HP = 746 W

Converting Amperes to Watts

Amperes measure electrical current (flow rate of charge). Watts measure electrical power (rate of energy use). You need voltage to convert between them because power depends on both current and voltage.

The Formula

Watts = Amps × Volts or inversely: Amps = Watts / Volts

For three-phase AC: Watts = √3 × V_line × I_line × Power Factor

How to Use This Calculator

Enter the current in amperes and the supply voltage. Select single-phase or three-phase and, for AC loads, enter the power factor (default 1.0 for resistive loads). Results show watts and kilowatts.

Practical Examples

Example 1: 10A appliance on 230V single phase = 10 × 230 = 2,300W (2.3 kW).

Example 2: 16A EV charger on 230V = 16 × 230 = 3,680W = 3.68 kW (about 15 km range per hour of charging).

Example 3: 30A circuit on 120V US outlet = 30 × 120 = 3,600W = 3.6 kW.

Why This Conversion Matters

  • Circuit breaker sizing: Breakers are rated in amps; loads are specified in watts. Convert to check compatibility.
  • Cable selection: Cable current capacity (ampacity) is in amps, but appliances are specified in watts.
  • Solar and battery systems: Inverters are rated in watts; charge controllers in amps.
  • Generator compatibility: Compare generator watt output to combined load wattage.