Watts to Amps Converter

Convert watts to amps (and amps to watts) at 12 V, 120 V, 240 V or any voltage, for DC, single-phase or three-phase AC with a power factor.

Power (watts)

Voltage (volts)

Current type

Power factor (0–1)

Current

12.5 A

Kilowatts

1.5 kW

Apparent power

1500 VA

Amps = watts ÷ (power factor × volts).

Watts to amps chart

Amps drawn at 12 V DC, 120 V and 240 V (power factor 1)
Watts	12 V	120 V	240 V
100 W	8.3333 A	0.83333 A	0.41667 A
300 W	25 A	2.5 A	1.25 A
500 W	41.667 A	4.1667 A	2.0833 A
750 W	62.5 A	6.25 A	3.125 A
1,000 W	83.333 A	8.3333 A	4.1667 A
1,200 W	100 A	10 A	5 A
1,500 W	125 A	12.5 A	6.25 A
1,800 W	150 A	15 A	7.5 A
2,000 W	166.67 A	16.667 A	8.3333 A
2,400 W	200 A	20 A	10 A
3,000 W	250 A	25 A	12.5 A
5,000 W	416.67 A	41.667 A	20.833 A

The formulas

Direct current: amps = watts ÷ volts. A volt is defined as one watt per ampere (NIST Special Publication 811, Table 3), so 1,800 W on a 120 V circuit draws 1,800 ÷ 120 = 15 A.

Single-phase AC: amps = watts ÷ (power factor × volts). Three-phase AC with line-to-line voltage: amps = watts ÷ (√3 × power factor × volts), where √3 ≈ 1.732. Going the other way, watts = amps × volts × power factor (× √3 for three-phase).

Power factor, and when it matters

Power factor is the share of the current that does useful work. Heaters, kettles, toasters and incandescent bulbs are resistive, with a power factor of 1, so watts ÷ volts is exact. Motors, compressors and some power supplies have a lower power factor, which means they draw more current than their wattage suggests — use the figure on the nameplate or in the manual if it is given.

Generators, UPS units and transformers are rated in volt-amperes (VA), the current × voltage before power factor. That is why a 1,000 VA UPS cannot always run a 1,000 W load.

Sizing a circuit

The amps figure is what the load draws, not the breaker size. Electrical codes add margins — for example for loads that run for hours at a time — and wire length, temperature and the appliance's start-up surge all matter, so use this as a starting point and follow your local code or an electrician for anything you wire in.

Frequently asked questions

How many amps is 1500 watts at 120 volts?

12.5 amps (1,500 ÷ 120). At 240 volts the same 1,500 W heater draws 6.25 amps.

How many watts can a 15 amp, 120 volt circuit carry?

15 × 120 = 1,800 watts at most; a 20 A, 120 V circuit carries 2,400 W. Codes generally keep continuous loads well below the breaker's rating.

How many amps does 1000 watts draw?

About 8.33 A at 120 V, 4.17 A at 240 V and 83.3 A at 12 V DC — the lower the voltage, the higher the current.

How do I convert watts to amps for three-phase power?

Divide the watts by √3 × the line-to-line voltage × the power factor. 10 kW at 208 V with a power factor of 1 is 10,000 ÷ (1.732 × 208) ≈ 27.8 A per line.

Can I convert watts to amps without the voltage?

No. Watts are volts × amps, so the same wattage is a different current at every voltage. In the US, household outlets are 120 V and large appliances 240 V.