Amps to kW Calculator
ampstokw.com • Current → Power

Amps to Kilowatts Calculator

Convert amps to kW for DC, single-phase, and three-phase circuits in real time.

Decimals:
2

Use line-to-line voltage for 3-phase when selected above.

RMS current per line or phase, depending on system type.

For AC only. Typical values: 0.8 for motors, 1.0 for purely resistive loads.

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Enter voltage, current, and power factor to see kW.
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How amps to kW works

This tool converts electrical current (amps) into active power (kilowatts) using the standard formulas for DC, single-phase AC, and three-phase AC systems. You enter voltage, current, and power factor, and the calculator updates kW instantly as you type.

DC amps to kilowatts calculation

For direct current (DC) circuits, there is no power factor term. The relationship between current and power is: 

kW = (V × I) ÷ 1000
Where:
  V = voltage in volts (V)
  I = current in amps (A)

Example: A 48 V DC supply feeding 50 A delivers kW = (48 × 50) ÷ 1000 = 2.4 kW.

AC single phase amps to kilowatts calculation

For single-phase AC systems, the active power also depends on power factor (PF), which represents how effectively current is converted into useful work: 

kW = (V × I × PF) ÷ 1000
Where:
  V  = RMS voltage in volts
  I  = RMS current in amps
  PF = power factor (0–1)

Example: 230 V single-phase circuit, 16 A, PF = 0.8 → kW = (230 × 16 × 0.8) ÷ 1000 ≈ 2.94 kW.

AC three phase amps to kilowatts calculation

Three-phase systems can be expressed using either line-to-line voltage (VLL) or line-to-neutral voltage (VLN). The calculator lets you choose which one you use.

Calculation with line to line voltage

kW = √3 × V_LL × I × PF ÷ 1000

Example: 400 V three-phase, 25 A per line, PF = 0.85 → kW ≈ 1.732 × 400 × 25 × 0.85 ÷ 1000 ≈ 14.7 kW.

Calculation with line to neutral voltage

kW = 3 × V_LN × I × PF ÷ 1000

Example: 230 V line-to-neutral, 25 A per phase, PF = 0.85 → kW = 3 × 230 × 25 × 0.85 ÷ 1000 ≈ 14.7 kW.

Typical power factor values

Real-world power factor depends on the load. The table below shows typical ranges:

Load type Typical PF (lagging)
Resistive heaters / incandescent lamps ≈ 1.0
Small induction motors (lightly loaded) 0.60–0.75
Standard industrial motors (normal load) 0.80–0.90
High-efficiency motors with correction 0.95–0.99
Fluorescent/LED lighting with modern drivers 0.90–0.98

When in doubt, using PF = 0.8 is a reasonable starting point for many motor loads. You can always update the value if you know the exact power factor from the nameplate or specs.

FAQs

How many kW is 1 Amp?
It depends on voltage and power factor. For a typical single-phase 230 V circuit at power factor 0.8:

kW = (V × I × PF) ÷ 1000 = (230 × 1 × 0.8) ÷ 1000 ≈ 0.184 kW.

If voltage or PF changes, the kW value for 1 amp changes with it.
How many amps is 1kW?
Rearrange the single-phase formula to solve for current:

I = (kW × 1000) ÷ (V × PF).

Example at 230 V, PF = 0.8:
I ≈ 1000 ÷ (230 × 0.8) ≈ 5.43 amps.

You can enter 1 kW and adjust voltage and PF in the calculator to see the exact current for your case (by trial until kW is close to 1).
How many kW is 20 amps?
Use the same formula and plug in I = 20 A. For a 230 V single-phase circuit at PF = 0.8:

kW = (230 × 20 × 0.8) ÷ 1000 = 3680 ÷ 1000 ≈ 3.68 kW.

Change the voltage or power factor in the calculator and the result will update instantly.
How do you convert amps to kW in 3-phase?
For three-phase systems there are two common formulas:
  • Line-to-line voltage: kW = √3 × VLL × I × PF ÷ 1000
  • Line-to-neutral voltage: kW = 3 × VLN × I × PF ÷ 1000
Pick the matching option in the calculator (line-to-line or line-to-neutral), enter voltage, amps, and power factor, and the three-phase kW value is calculated for you automatically.