How do I convert amps to watts?

To convert amps to watts, multiply amps by volts. For DC, Watts = Amps × Volts. For single-phase AC real power, Watts = Amps × Volts × Power Factor. For three-phase line-to-line voltage, Watts = √3 × Amps × Volts × Power Factor.

What is the amps to watts formula for DC?

For DC circuits, use W = A × V. Example: 10 amps at 12 volts is 120 watts. DC circuits do not use power factor because the current does not alternate in phase with the voltage.

What is the single-phase amps to watts formula?

For single-phase AC, use W = A × V × PF. If power factor is 1, the formula becomes watts = amps × volts. If the load has a power factor of 0.8, the real watts are 80% of the apparent volt-amps.

What is the three-phase amps to watts formula?

For three-phase AC using line-to-line voltage, use W = √3 × A × V × PF. If you are using line-to-neutral voltage, use W = 3 × A × V × PF. Most three-phase supply voltages are line-to-line values.

Can I calculate watts without voltage?

No. Amps alone only tells you current. To calculate watts, you need voltage as well. One amp at 12 volts is 12 watts, but one amp at 240 volts is 240 watts before power factor.

Is watts the same as volt-amps?

Watts and volt-amps are the same only when power factor is 1. In AC circuits, watts measure real power and volt-amps measure apparent power. The relationship is Watts = VA × Power Factor.

How many watts is 1 amp at 120 volts?

At 120 volts DC or single-phase AC with PF 1, 1 amp is 120 watts. At PF 0.8, 1 amp is 96 watts of real power and 120 VA of apparent power.

How many watts is 1 amp at 240 volts?

At 240 volts and PF 1, 1 amp is 240 watts. At PF 0.8, 1 amp is 192 watts. For 240 V three-phase line-to-line at PF 1, 1 amp is about 416 watts.

How many watts is 10 amps at 120 volts?

At 120 volts and PF 1, 10 amps is 1,200 watts. If the load is AC with PF 0.8, the real power is 960 watts while the apparent power is 1,200 VA.

How many watts is 30 amps at 240 volts?

At 240 volts single-phase and PF 1, 30 amps is 7,200 watts. At PF 0.8, it is 5,760 watts. For a three-phase 240 V line-to-line circuit at PF 0.8, it is about 9,976 watts.

What is the difference between watts and kilowatts?

A kilowatt is 1,000 watts. To convert watts to kW, divide by 1,000. To convert kW to watts, multiply by 1,000. Example: 2,400 watts equals 2.4 kW.

Can I convert amps to kWh?

Yes, but you need time. First convert amps to watts, then convert watts to kW, then multiply by hours. Formula: kWh = Watts ÷ 1000 × Hours. A 1,200 W load running for 5 hours uses 6 kWh.

Can I use amps and ohms to calculate watts?

Yes. If you know current and resistance, use W = A² × Ω. This is often used for resistive heating and electrical loss calculations. It should not replace full AC power calculations for complex motor or reactive loads.

Why does a motor use more amps than the watts suggest?

Motors can have power factor below 1, efficiency losses, and high starting current. The running watts may be lower than volts times amps because part of the apparent power is reactive power, and some input power is lost as heat.

Is this calculator suitable for electrical safety design?

It is suitable for estimating electrical power, but wiring, breakers, plugs, and protection devices must be selected using local electrical codes, manufacturer data, load type, continuous-load rules, and qualified judgment.

Engineering

Amps to Watts Calculator

Convert amps to watts using voltage, circuit type, and power factor. Supports DC, AC single-phase, AC three-phase, watts to amps, and the resistance formula W = A² × Ω.

Current (amps)

Circuit type

Common voltage

Voltage (volts)

Power factor (PF)

Runtime optional, hours

Real power

—

Kilowatts—

Apparent power—

Horsepower equivalent—

Energy for runtime—

Formula used—

Amps to watts formulas

The amps-to-watts conversion changes depending on whether the circuit is DC, AC single-phase, or AC three-phase. For AC real power, include power factor.

DC: W = A × V AC single-phase: W = A × V × PF AC three-phase using line-to-line voltage: W = √3 × A × V × PF AC three-phase using line-to-neutral voltage: W = 3 × A × V × PF Using resistance: W = A² × Ω

Amps to watts conversion table

Current	12 V DC	120 V 1φ PF 1	230 V 1φ PF 1	400 V 3φ PF 1
1 A	12 W	120 W	230 W	693 W
2 A	24 W	240 W	460 W	1,386 W
5 A	60 W	600 W	1,150 W	3,464 W
10 A	120 W	1,200 W	2,300 W	6,928 W
15 A	180 W	1,800 W	3,450 W	10,392 W
20 A	240 W	2,400 W	4,600 W	13,856 W
30 A	360 W	3,600 W	6,900 W	20,785 W
40 A	480 W	4,800 W	9,200 W	27,713 W
50 A	600 W	6,000 W	11,500 W	34,641 W
100 A	1,200 W	12,000 W	23,000 W	69,282 W

Table values assume power factor 1 unless noted. For motors and other AC inductive loads, use the calculator with the correct power factor.

Worked examples

Example 1 — 10 A at 120 V DC W = 10 × 120 = 1,200 W Example 2 — 15 A at 230 V single-phase, PF 0.9 W = 15 × 230 × 0.9 = 3,105 W Example 3 — 20 A at 400 V three-phase line-to-line, PF 0.8 W = √3 × 20 × 400 × 0.8 = 11,085 W Example 4 — 5 A through 10 Ω resistance W = 5² × 10 = 250 W

Watts, kW, VA, and kVA

Watts measure real power. Volt-amps measure apparent power. In DC circuits or AC circuits with power factor 1, watts and VA are numerically the same. In AC circuits with lower power factor, apparent power is higher than real power.

Use kW for real electrical power and energy cost estimates. Use kVA when sizing generators, UPS systems, transformers, and apparent power capacity. The relationship is Watts = VA × PF.

Common questions

To convert amps to watts, multiply amps by volts. For DC, Watts = Amps × Volts. For single-phase AC real power, Watts = Amps × Volts × Power Factor. For three-phase line-to-line voltage, Watts = √3 × Amps × Volts × Power Factor.
For DC circuits, use W = A × V. Example: 10 amps at 12 volts is 120 watts. DC circuits do not use power factor because the current does not alternate in phase with the voltage.
For single-phase AC, use W = A × V × PF. If power factor is 1, the formula becomes watts = amps × volts. If the load has a power factor of 0.8, the real watts are 80% of the apparent volt-amps.
For three-phase AC using line-to-line voltage, use W = √3 × A × V × PF. If you are using line-to-neutral voltage, use W = 3 × A × V × PF. Most three-phase supply voltages are line-to-line values.
No. Amps alone only tells you current. To calculate watts, you need voltage as well. One amp at 12 volts is 12 watts, but one amp at 240 volts is 240 watts before power factor.
Watts and volt-amps are the same only when power factor is 1. In AC circuits, watts measure real power and volt-amps measure apparent power. The relationship is Watts = VA × Power Factor.
At 120 volts DC or single-phase AC with PF 1, 1 amp is 120 watts. At PF 0.8, 1 amp is 96 watts of real power and 120 VA of apparent power.
At 240 volts and PF 1, 1 amp is 240 watts. At PF 0.8, 1 amp is 192 watts. For 240 V three-phase line-to-line at PF 1, 1 amp is about 416 watts.
At 120 volts and PF 1, 10 amps is 1,200 watts. If the load is AC with PF 0.8, the real power is 960 watts while the apparent power is 1,200 VA.
At 240 volts single-phase and PF 1, 30 amps is 7,200 watts. At PF 0.8, it is 5,760 watts. For a three-phase 240 V line-to-line circuit at PF 0.8, it is about 9,976 watts.
A kilowatt is 1,000 watts. To convert watts to kW, divide by 1,000. To convert kW to watts, multiply by 1,000. Example: 2,400 watts equals 2.4 kW.
Yes, but you need time. First convert amps to watts, then convert watts to kW, then multiply by hours. Formula: kWh = Watts ÷ 1000 × Hours. A 1,200 W load running for 5 hours uses 6 kWh.
Yes. If you know current and resistance, use W = A² × Ω. This is often used for resistive heating and electrical loss calculations. It should not replace full AC power calculations for complex motor or reactive loads.
Motors can have power factor below 1, efficiency losses, and high starting current. The running watts may be lower than volts times amps because part of the apparent power is reactive power, and some input power is lost as heat.
It is suitable for estimating electrical power, but wiring, breakers, plugs, and protection devices must be selected using local electrical codes, manufacturer data, load type, continuous-load rules, and qualified judgment.