Watts to Amps Calculator
Convert power (watts) to current (amps) at any voltage — or flip it and convert amps to watts. Pick a voltage preset or enter your own; the calculator warns when a load is too heavy for a standard household circuit.
Current draw
12.5 A
Implied resistance: 9.60 Ω⚠ Over 12 A — too much for a shared 15 A household circuit (80% rule).
Uses watts = volts × amps (resistive/DC loads). Motor-driven AC appliances may draw 10–25% more current than calculated due to power factor.
How the Conversion Works
Watts, volts, and amps are linked by one relationship: power equals voltage times current. Watts alone can't convert to amps — the voltage decides how much current a given power level draws. The same 1,500 W heater pulls 12.5 A from a US 120 V outlet but only 6.5 A from a European 230 V outlet.
Formulas
Amps = Watts ÷ Volts Watts = Volts × Amps Example (US outlet): 1,500 W ÷ 120 V = 12.5 A Circuit capacity (80% continuous rule): 15 A breaker → 12 A continuous → 1,440 W at 120 V 20 A breaker → 16 A continuous → 1,920 W at 120 V
Frequently Asked Questions
How many amps does a 1,500-watt space heater draw?
On a standard US 120 V circuit: 1,500 ÷ 120 = 12.5 amps. That's over 80% of a 15-amp circuit's capacity, which is why space heaters should run alone on a circuit — adding almost anything else trips the breaker.
Should I enter 120 or 240 volts for my appliance?
Most US household outlets are 120 V. The exceptions run on dedicated 240 V circuits: electric dryers, ranges, water heaters, central AC, and EV chargers (their plugs look visibly different). In Europe and most of the world, use 230 V.
My device label lists both watts and amps — why?
Manufacturers list both for convenience: watts describe energy consumption (what you pay for), amps describe circuit load (what the wiring must handle). They're consistent with each other at the stated voltage — watts = volts × amps.
What is power factor and do I need to worry about it?
For AC devices like motors and some electronics, real power is volts × amps × power factor, where power factor is between 0 and 1. Resistive loads (heaters, incandescent bulbs, kettles) have a power factor of 1, so the simple formula is exact. For motor-driven appliances, the label amps may read 10–25% higher than watts ÷ volts would suggest.