A 1,500 W heater on 120 V
1,500 ÷ 120 = 12.5 A.
Watts, Amps and Volts Converter
Convert between watts, amps and volts for DC, single-phase and three-phase AC, with power factor.
Result
Enter your values and select Calculate to see the result.
Runs in your browser — nothing you enter is sent to a server.
How the Watts, Amps and Volts Converter works
Choose what to find — watts, amps or volts — and the type of supply. For AC, enter the power factor: 1 for heaters and kettles, lower for motors and many power supplies. Three-phase uses the line-to-line voltage (for example 400 V or 480 V). The result also shows apparent power in volt-amperes for AC.
Formulas
DC
P = V × I
AC single-phase
P = V × I × PF
AC three-phase
P = √3 × V × I × PF
Examples
A three-phase motor
400 V, 10 A and a power factor of 0.85: √3 × 400 × 10 × 0.85 ≈ 5,889 W.
Frequently asked questions
What is power factor?
The share of current that does useful work. Motors draw extra current that flows back and forth, so PF is below 1.
Watts or VA?
Watts are real power; VA is apparent power. UPS and generator ratings often use VA.
How do I get amps for a circuit breaker?
Calculate the current, then follow your local rules for breaker and cable sizing — often with a safety margin.
Information:
Good to know
Estimates for planning. Follow local building codes and the manufacturer's instructions, and use a qualified professional for structural or electrical work.
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