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Conversions · kW = A × V ÷ 1000

Amps to kW Calculator — DC, Single-Phase & Three-Phase

To convert amps to kilowatts, multiply by the voltage (and power factor for AC), then divide by 1000. Single-phase: kW = amps × V × PF ÷ 1000. Three-phase: √3 × amps × V × PF ÷ 1000. Enter your numbers below.

Dr. Artie Vance Written and reviewed by Dr. Artie Vance, Ph.D. Physics, MIT · 14 years' experience · Updated August 26, 2026
Amps → kW Calculator Live
Convert amps to kilowatts
Pick the system, then enter the amps, volts, and power factor.
Resistive = 1.0 · motors ≈ 0.8
Power 12kW
Single-phase: 50 × 240 × 1.00 ÷ 1000 = 12 kW  (12,000 W)
Now size the wire & breaker →
Three-phase uses line-to-line voltage. Power factor matters for motors and reactive loads — resistive loads (heaters) are 1.0.

How to convert amps to kW (the formula)

Power is voltage times current, and a kilowatt is 1000 watts — so amps become kilowatts once you know the voltage (and, on AC, the power factor), then divide by 1000. Three cases:

SystemFormulaExample
DCkW = A × V ÷ 100050 A × 240 V = 12 kW
AC single-phasekW = A × V × PF ÷ 100050 A, 240 V, PF 1 = 12 kW
AC three-phasekW = √3 × A × V × PF ÷ 100050 A, 480 V, PF 1 = 41.57 kW

The √3 (about 1.732) handles three-phase, and the ÷ 1000 turns watts into kilowatts. If you want plain watts instead, skip that last step — or use the amps to watts calculator.

How many kW is X amps?

The common currents converted to kilowatts at power factor 1.0 (single-phase):

Current120 V240 V
10 A1.2 kW2.4 kW
20 A2.4 kW4.8 kW
30 A3.6 kW7.2 kW
50 A6 kW12 kW
100 A12 kW24 kW

For three-phase, the same current gives more kilowatts because of the √3 — for example, 50 A at 480 V three-phase is about 41.57 kW, and 40 A is 33.26 kW. At the common European/industrial 415 V, 30 A three-phase is about 21.56 kW.

Services & generators

This is the conversion behind matching a generator (rated in kW) to a panel or breaker (rated in amps), and for sizing a service. A 200 A, 240 V service can deliver up to about 48 kW, and a 400 A service about 96 kW. Going the other way, a 20 kW generator at 240 V single-phase supplies roughly 83 A.

Power factor and three-phase

On AC, the real power in kilowatts is amps × volts × power factor ÷ 1000. Resistive loads (heaters) are power factor 1.0; motors run around 0.8, which gives fewer kilowatts for the same amps. Three-phase adds an extra √3, which is why 415 V and 480 V systems carry so much power:

Power factor in action

20 A at 240 V:
• at PF 1.0 (resistive) → 4.8 kW
• at PF 0.8 (motor) → 3.84 kW of real power
And three-phase: 50 A at 480 V → 41.57 kW.

These all connect. 1 kW = 1000 W, so for watts instead of kilowatts use amps to watts. For the reverse — a kW rating back to amps — use kW to amps. And for apparent power, remember kW = kVA × power factor; the kVA to amps page covers that side.

From amps to the circuit (size the wire and breaker)

Size the breaker and wire from the amps, not the kilowatts — and remember the NEC 125% rule for continuous loads (running three hours or more). Run the current through the Wire Size Calculator and the Breaker Size Calculator, and the AWG ampacity chart has the conductor ratings.

Frequently asked questions

ConversionsWhat is the formula to convert amps to kW?
kW = amps × volts × power factor ÷ 1000 for single-phase, or √3 × amps × volts × power factor ÷ 1000 for three-phase. For DC, it is amps × volts ÷ 1000.
⚡ Size the circuit →
ConversionsHow many kW is 20 amps?
4.8 kW at 240 volts and 2.4 kW at 120 volts, single-phase at power factor 1.0.
ConversionsHow many kW is 50 amps?
12 kW at 240 volts, single-phase at power factor 1.0. At 120 volts it is 6 kW.
ConversionsHow many kW is 100 amps?
24 kW at 240 volts, single-phase at power factor 1.0. On three-phase at 480 volts, 100 amps is about 83 kW.
ConversionsHow do I convert amps to kW for three-phase?
Multiply √3 by the amps, the line-to-line volts, and the power factor, then divide by 1000: kW = 1.732 × amps × volts × PF ÷ 1000.
ConversionsDoes power factor change amps to kW?
Yes. A lower power factor gives fewer real kilowatts for the same amps. Resistive loads are power factor 1.0; motors run around 0.8.
ConversionsHow do I convert amps to kW at 240V?
Multiply the amps by 240 and the power factor, then divide by 1000. For example, 50 amps × 240 ÷ 1000 is 12 kW at power factor 1.0.
ConversionsHow many kW is 30 amps?
7.2 kW at 240 volts and 3.6 kW at 120 volts, single-phase at power factor 1.0.
Dr. Artie Vance
Dr. Artie Vance
Technical reviewer · Ph.D. in Physics, MIT · 14 years' experience · Formulas verified against IEEE / NEC conventions

This calculator gives estimates from the standard power formula. Real AC loads vary with power factor, and circuit sizing follows the NEC and your local authority having jurisdiction (AHJ). When in doubt, hire a licensed electrician.