Calculators · Watts to Amps Calculator

Electrical

Watts to Amps Calculator

Convert watts to amps or amps to watts for DC, single-phase and three-phase circuits. Type the power, the voltage and the power factor.

Type of circuit

DC, single-phase AC or three-phase AC.

Power

mW is milliwatts and MW is megawatts.

Voltage (V)

The voltage across the load, in volts.

Power factor (PF)

Above 0 and up to 1. Use 1 for a purely resistive load.

Common nominal voltages (tap one to use it)

DC examples

How to convert watts to amps

Watts measure power and amps measure current. The link between them is the voltage. At the same power, a higher voltage means fewer amps. A purely DC circuit is the simplest case. In AC circuits the power factor (PF), the ratio of real power in watts to apparent power in volt-amps, also matters, and three-phase circuits add a factor of √3.

Circuit	Watts to amps	Amps to watts
DC	I = P ÷ V	P = I × V
AC single-phase	I = P ÷ (V × PF)	P = I × V × PF
AC three-phase	I = P ÷ (√3 × V × PF)	P = √3 × I × V × PF

I is the current in amps, P the power in watts, V the voltage in volts and PF the power factor. In the three-phase row, V is the line-to-line voltage. These are the same formulas an informational calculator site lists, which we opened in October 2026 to compare. A purely resistive load has a PF of 1, and then the single-phase formula gives the same answer as the DC one. If you know the resistance instead of the power, use the Ohm's law calculator.

Example 1: a 5,000 W load on a 240 V single-phase circuit

A load is rated 5,000 W, runs on 240 V single-phase AC and has a power factor of 0.9. In the calculator, choose "AC single-phase" and type those three numbers.

Step	Operation	Result
Voltage times power factor	240 × 0.9	216
Current	5,000 ÷ 216	23.148 A
Apparent power	5,000 ÷ 0.9	5,555.56 VA

Example 2: a 10 kW load on a 208 V three-phase circuit

A load draws 10 kW on a 208 V line-to-line three-phase circuit with a power factor of 0.85. Choose "AC three-phase", keep "Line-to-line", set the unit to kW and type 10.

Step	Operation	Result
Power in watts	10 × 1,000	10,000 W
√3 times voltage	1.7321 × 208	360.27
Times power factor	360.27 × 0.85	306.23
Current	10,000 ÷ 306.23	32.656 A

Watts to amps chart

Amps for common wattages at several voltages, for DC or AC with a power factor of 1. Divide the watts by the volts to check any cell. For another power factor, divide the result by it.

Watts	12 V	24 V	120 V	240 V	480 V
100 W	8.33	4.17	0.83	0.42	0.21
500 W	41.67	20.83	4.17	2.08	1.04
1,000 W	83.33	41.67	8.33	4.17	2.08
1,500 W	125.00	62.50	12.50	6.25	3.13
1,800 W	150.00	75.00	15.00	7.50	3.75
2,000 W	166.67	83.33	16.67	8.33	4.17
3,000 W	250.00	125.00	25.00	12.50	6.25
5,000 W	416.67	208.33	41.67	20.83	10.42
7,500 W	625.00	312.50	62.50	31.25	15.63
10,000 W	833.33	416.67	83.33	41.67	20.83

Three-phase amps chart

Line current for a balanced three-phase load, with the line-to-line voltage. The power factor of 0.85 is only an example. Use the value for your own equipment.

Power	208 V, PF 1	208 V, PF 0.85	240 V, PF 1	240 V, PF 0.85	480 V, PF 1	480 V, PF 0.85
5 kW	13.88	16.33	12.03	14.15	6.01	7.08
10 kW	27.76	32.66	24.06	28.30	12.03	14.15
15 kW	41.64	48.98	36.08	42.45	18.04	21.23
25 kW	69.39	81.64	60.14	70.75	30.07	35.38
50 kW	138.79	163.28	120.28	141.51	60.14	70.75

How the power factor changes the amps

For the same wattage, a lower power factor means more current. This table uses 5,000 W on a 240 V single-phase circuit. The extra current is 1 ÷ PF − 1.

Power factor	Amps	More than at PF 1
1	20.83	0%
0.95	21.93	5.3%
0.9	23.15	11.1%
0.85	24.51	17.6%
0.8	26.04	25.0%
0.7	29.76	42.9%

The calculator starts with a power factor of 1, which is right for a purely resistive load. For anything else, look for the power factor on the nameplate or in the data sheet. If you do not know it, the result at PF 1 is the lowest the current can be, and a real load will draw at least that much.

Which voltage to use

The buttons under the voltage field are examples of nominal system voltages. The values 120, 208, 240, 277 and 480 volts are the ones in the table that PG&E publishes to explain the ANSI C84.1 voltage standard (PG&E, Voltage Tolerance Boundary). PacifiCorp's table of service voltages lists 120/240 V single-phase and 208Y/120 V and 480Y/277 V three-phase systems (PacifiCorp, Voltage Level and Range). We read both documents in October 2026. We did not read the ANSI standard itself. The 12 V and 24 V buttons are only DC examples.

The actual voltage at your equipment can differ from the nominal value, so use the voltage on the nameplate or the one you measured. In a pair like 208Y/120, the larger number is the line-to-line voltage, because the line-to-line voltage is √3 times the line-to-neutral one (120 × 1.7321 = 207.8). The three-phase formula needs the line-to-line number.

What this calculator does not do

It gives the current from the numbers you type, for a balanced load. It does not choose a wire gauge, a breaker or a fuse, and it does not apply any margin. The electrical code in force where you live sets those rules, and a licensed electrician should size and protect the circuit. Nothing you type leaves your browser.

Frequently asked questions

How do you convert watts to amps?

Divide the watts by the volts. For a DC circuit, amps = watts ÷ volts. For single-phase AC, also divide by the power factor, so amps = watts ÷ (volts × power factor). For three-phase AC, amps = watts ÷ (√3 × line-to-line volts × power factor). If the power factor is 1, the AC single-phase formula is the same as the DC one.

How many amps is 1,000 watts?

It depends on the voltage. With a power factor of 1, 1,000 watts is 8.33 amps at 120 volts, 4.17 amps at 240 volts and 83.33 amps at 12 volts. The lower the voltage, the more amps the same wattage draws.

What is 1,500 watts in amps?

At 120 volts and a power factor of 1, 1,500 watts is 1,500 ÷ 120 = 12.5 amps. At 240 volts it is 6.25 amps. If the load has a power factor below 1, the current is higher, for example 13.89 amps at 120 volts and a power factor of 0.9.

How many amps is 200 watts at 240 volts?

With a power factor of 1, 200 ÷ 240 = 0.83 amps. With a power factor of 0.9 it is 200 ÷ (240 × 0.9) = 0.93 amps. In DC the power factor does not apply, so 200 watts at 240 volts DC is 0.83 amps.

What power factor should I use?

Use the value on the nameplate or data sheet of the equipment if it lists one. A purely resistive load has a power factor of 1, and that is the default in the calculator. A power factor of 1 gives the smallest possible current for a given wattage, so a real load with a lower power factor draws more amps than the result shown. This page does not suggest typical values for motors or other equipment.

Which voltage do I use for a three-phase circuit?

The formula uses the line-to-line voltage, the voltage measured between two of the three lines. It is √3 times the line-to-neutral voltage. In a 208Y/120 system the line-to-line voltage is 208 and the line-to-neutral voltage is 120. If you only have the line-to-neutral number, choose that option in the calculator and it converts it for you.

Can I use this to choose a wire size or a breaker?

No. The result is only the current the load draws from the numbers you type. Wire size and breaker size depend on more than that, and the electrical code adopted where you live adds margins and other requirements that this calculator does not apply. Ask a licensed electrician.

How do I convert amps to watts?

Multiply the amps by the volts. For DC, watts = amps × volts. For single-phase AC, watts = amps × volts × power factor. For three-phase AC, watts = √3 × amps × line-to-line volts × power factor. For example, 15 amps at 120 volts is 1,800 watts. Use the "Amps to watts" tab.