Amps to kW Calculator
- Last reviewed:
- | Reviewed to ensure accurate amps-to-kw conversions for DC, single-phase, and three-phase circuits.
Table of Contents
Use this amps to kW calculator to convert electrical current into kilowatts for DC, single-phase and three-phase circuits. Enter your amps and voltage to see the result in kW and watts, with the full formula and step-by-step working shown.
Amps to kW Calculator
Enter your values below to get your result with full working shown
Enter the current in amperes (A)
Leave at 1 for a simple learning example. Motors and inductive loads typically use 0.7–0.95.
Result
—
kW
Formula Used
Values Substituted
Step-by-Step Working
Also Expressed As
Plain English Explanation
Amps to kW Formula
To convert amps to kilowatts, multiply the current by the voltage to get watts, then divide by 1,000 to convert to kilowatts.
DC circuits: kW = (I × V) ÷ 1,000
Single-phase AC circuits: kW = (I × V × PF) ÷ 1,000
Three-phase AC circuits: kW = (√3 × I × V × PF) ÷ 1,000
Where:
- kW = Power in kilowatts
- I = Current in amps (A)
- V = Voltage in volts (V)
- PF = Power factor (0–1)
- √3 = Three-phase constant, approximately 1.732
Worked Example
UK single-phase example: A circuit carries 32 A at 230 V single-phase with a power factor of 1.
Step 1: I × V × PF = 32 × 230 × 1 = 7,360 W Step 2: Convert to kW: 7,360 ÷ 1,000 = 7.36 kW
UK three-phase example: A three-phase motor draws 17 A per phase at 400 V with a power factor of 0.85.
Step 1: √3 × I × V × PF = 1.732 × 17 × 400 × 0.85 = 10,002 W Step 2: Convert to kW: 10,002 ÷ 1,000 = 10.0 kW
US single-phase example: A circuit carries 20 A at 120 V single-phase with a power factor of 1.
Step 1: I × V × PF = 20 × 120 × 1 = 2,400 W Step 2: Convert to kW: 2,400 ÷ 1,000 = 2.4 kW
Common Mistakes
- Forgetting to divide by 1,000. The formula gives you watts first. Always divide by 1,000 to convert to kilowatts. The calculator does this automatically.
- Using the wrong voltage. UK single-phase is 230 V. UK three-phase is 400 V line-to-line. US is 120 V or 240 V single-phase.
- Ignoring power factor on AC loads. Resistive loads such as heaters use PF = 1. Motors and inductive loads typically operate at 0.7–0.95, which reduces the real power output.
- Applying the single-phase formula to a three-phase load. Three-phase circuits use √3 (1.732) as a constant. Using the single-phase formula for a three-phase load will give a significantly wrong answer.
- Confusing kW with kVA. kW is real power. kVA is apparent power. They are only equal when the power factor is 1. For AC loads with a power factor below 1, kVA will always be higher than kW.
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Disclaimer: This calculator is provided for learning and revision purposes only. Results must not be used as the basis for electrical design, inspection, testing, verification or any on-site decision. Always seek advice from a competent qualified electrician or engineer.
Frequently Asked Questions
How do you convert amps to kW?
Multiply the current in amps by the voltage in volts to get watts, then divide by 1,000 to convert to kilowatts. For AC circuits, also multiply by the power factor.
What is the formula for amps to kW?
For DC: kW = (I × V) ÷ 1,000. For single-phase AC: kW = (I × V × PF) ÷ 1,000. For three-phase AC: kW = (√3 × I × V × PF) ÷ 1,000.
How many kW is 1 amp at 230 volts?
kW = (1 × 230 × 1) ÷ 1,000 = 0.23 kW (assuming power factor of 1).
How many kW is 1 amp at 120 volts?
kW = (1 × 120 × 1) ÷ 1,000 = 0.12 kW (assuming power factor of 1).
How many kW is 32 amps at 230 volts single-phase?
kW = (32 × 230 × 1) ÷ 1,000 = 7.36 kW (assuming power factor of 1).
What is the difference between kW and kVA?
kW is real power — the actual energy being converted into useful work. kVA is apparent power, which includes reactive power in AC circuits. The ratio between them is the power factor. For resistive loads, kW and kVA are equal.
Is this calculator suitable for electrical design?
No. This calculator is for learning and revision only. For electrical design, always refer to BS 7671 and consult a qualified electrician or engineer.
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