Watts to Amps Calculator
Watts alone can't tell you amps — you also need the voltage. The math is one line: amps = watts ÷ volts. Most US wall outlets are 120 volts (already filled in below), so a 1,500-watt heater pulls about 12.5 amps.
Voltage
12.5 amps
A 1500-watt load on a 120-volt circuit draws about 12.5 amps.
Will it trip the breaker? That's well within a 20-amp circuit (safe continuous limit 16A).
Runs in your browser — nothing is sent anywhere. Estimates assume nominal voltage and ideal conditions; confirm with a licensed electrician and local code before sizing wire or breakers.
Watts to amps table (120V & 240V)
| Watts | Amps @ 120V | Amps @ 240V |
|---|---|---|
| 100 W | 0.83 A | 0.42 A |
| 500 W | 4.17 A | 2.08 A |
| 1,000 W | 8.33 A | 4.17 A |
| 1,200 W | 10 A | 5 A |
| 1,500 W | 12.5 A | 6.25 A |
| 1,800 W | 15 A | 7.5 A |
| 2,000 W | 16.67 A | 8.33 A |
| 3,000 W | 25 A | 12.5 A |
| 5,000 W | 41.67 A | 20.83 A |
Resistive load (power factor 1). A motor draws a bit more — divide by ~0.8.
How many amps does a real appliance draw?
| Appliance | Watts | Amps @ 120V |
|---|---|---|
| LED TV | ~100 W | ~0.8 A |
| Microwave | ~1,000 W | ~8.3 A |
| Hair dryer | ~1,500 W | ~12.5 A |
| Space heater (near the limit of a 15A circuit) | ~1,500 W | ~12.5 A |
| Window AC (motor — a bit more on startup) | ~1,200 W | ~10 A |
| Toaster oven | ~1,800 W | ~15 A |
| Electric kettle | ~1,500 W | ~12.5 A |
The formula
Divide the watts by the voltage. Amps = Watts ÷ Volts. (For a motor or AC unit, divide once more by the power factor — about 0.8 — since they pull a little extra.)
Example: A 1,500-watt space heater on a standard 120-volt outlet: 1500 ÷ 120 = 12.5 amps.
One caveat that keeps people safe: This is a guide for estimation only. Conversions assume nominal voltage and ideal conditions; real installations vary with power factor, voltage drop, temperature, wire type, and continuous vs. brief use. It doesn't replace the National Electrical Code or a licensed electrician — always confirm with a pro and local code before sizing wire, breakers, or circuits.
Hiring out the wiring?
Before you pay anyone to touch your panel or wiring, make sure they're actually licensed. You can check a contractor's license on StateCreds — our sister site.
Verify a contractor's license by state →Common questions
- How many amps is 1500 watts?
- At 120 volts, 1,500 watts is 12.5 amps (1500 ÷ 120). At 240 volts it's half that — 6.25 amps. A 1,500W heater at 12.5A sits right near the comfortable limit of a 15-amp circuit.
- How many amps does a 1500W heater use, and will it trip my breaker?
- About 12.5 amps at 120V. A 15-amp circuit can safely carry ~12 amps continuously (the 80% rule), so the heater is fine on its own — but don't run much else on the same circuit or you may trip the breaker.
- Do I need to know the voltage?
- Yes — watts ÷ volts. The same wattage draws half the amps at 240V as at 120V. Pick the voltage that matches your situation above; 120V is the standard US outlet.
- Is this for AC or DC?
- Both, for a resistive load (heaters, bulbs). For an AC motor or compressor, set the power factor (~0.8) — those draw a bit more current than the simple formula shows.