kW to Amps Calculator
- Last reviewed:
- | Reviewed to ensure accurate kW-to-amps conversions for DC, single-phase, and three-phase circuits.
Table of Contents
Use this kW to amps calculator to convert kilowatts into current for DC, single-phase and three-phase circuits. Enter your kilowatts and voltage to see the result with the full formula and working shown — including the kW to watts conversion step.
kW to Amps Calculator
Enter your values below to get your result with full working shown
Enter value in kilowatts. For example, a 7,400 W load = 7.4 kW
Leave at 1 for a simple learning example. Motors and inductive loads typically use 0.7–0.95.
Result
—
A
kW Converted to Watts
Formula Used
Values Substituted
Step-by-Step Working
Plain English Explanation
kW to Amps Formula
To convert kilowatts to amps, you first multiply the kW value by 1,000 to convert it to watts. Then apply the standard watts to amps formula for your circuit type.
DC circuits: I = (kW × 1,000) ÷ V
Single-phase AC circuits: I = (kW × 1,000) ÷ (V × PF)
Three-phase AC circuits: I = (kW × 1,000) ÷ (√3 × V × PF)
Where:
- I = Current in amps (A)
- kW = Power in kilowatts
- V = Voltage in volts (V)
- PF = Power factor (0–1)
- √3 = Three-phase constant, approximately 1.732
Worked Example
UK single-phase example: A 7.4 kW electric shower is connected to a 230 V single-phase supply with a power factor of 1.
Step 1: Convert kW to watts: 7.4 × 1,000 = 7,400 W Step 2: I = 7,400 ÷ (230 × 1) = 32.17 A
UK three-phase example: A 10 kW motor is connected to a 400 V three-phase supply with a power factor of 0.85.
Step 1: Convert kW to watts: 10 × 1,000 = 10,000 W Step 2: I = 10,000 ÷ (1.732 × 400 × 0.85) = 17.01 A per phase
US single-phase example: A 7.4 kW load on a 120 V supply with a power factor of 1:
Step 1: Convert kW to watts: 7.4 × 1,000 = 7,400 W Step 2: I = 7,400 ÷ (120 × 1) = 61.67 A
Common Mistakes
- Entering watts instead of kilowatts. If your value is already in watts, use the Watts to Amps Calculator instead. For example, 7,400 W should be entered as 7.4 kW here.
- 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.
- Applying the single-phase formula to a three-phase load. Always use the three-phase formula, which includes √3 (1.732), for three-phase circuits.
- 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.
- Using this result as a final cable or breaker size. Current is only the starting point. Always refer to BS 7671 for full design calculations.
Related Elec Training Courses
By Charanjit Mannu
Director, Elec Training
Based on real training delivery, learner outcomes, and current UK electrical regulations.
- City & Guilds Approved
- 4.8★ Google Reviews
- 1000+ Electricians Trained
Prefer a callback?
- City & Guilds
- 4.8 Trustpilot
- JIB Recognized
- 1,000+ Trained
£2707.50 (£3249.00 Inc VAT)
Level 2 Diploma - C&G 2365-02
This qualification is the first step on the ladder to becoming a fully qualified electrician.
£2707.50 (£3249.00 Inc VAT)
Level 3 Diploma - C&G 2366-03
Fully updated to the latest City & Guilds standard, this Level 3 course builds seamlessly on your Level 2 foundations. Master advanced electrical theory and practical applications.
£499.17 (£599.00 inc VAT)
18th Edition Course – C&G 2382-26
This five-day BS 7671 course covers the new Amendment 4 regulations; it’s a mandatory requirement for electricians looking to remain compliant and up to date in the industry.
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 kW to amps?
Multiply your kW value by 1,000 to get watts, then divide by the voltage. For AC circuits, also divide by the power factor. Use the calculator above to see the full step-by-step working.
What is the formula for kW to amps?
For DC: I = (kW × 1,000) ÷ V. For single-phase AC: I = (kW × 1,000) ÷ (V × PF). For three-phase AC: I = (kW × 1,000) ÷ (√3 × V × PF).
How many amps is 1 kW at 230 volts?
1 kW = 1,000 W. I = 1,000 ÷ 230 = 4.35 amps (assuming power factor of 1).
How many amps is 1 kW at 120 volts?
1 kW = 1,000 W. I = 1,000 ÷ 120 = 8.33 amps (assuming power factor of 1).
How many amps is 10 kW three-phase at 400 volts?
I = (10,000) ÷ (1.732 × 400 × 1) = 14.43 amps per phase (assuming power factor of 1).
What is the difference between kW and kVA?
kW is real power — the actual work being done. kVA is apparent power, which includes reactive power in AC circuits. The power factor is the ratio between the two. For purely 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.
Related Calculators
Amps to Watts Calculator
Convert electrical current (amps) into power (watts)
Watts to Amps Calculator
Convert power (watts) into electrical current
Amps to kW Calculator
Convert electrical current (amps) into kilowatts (kW)
Ohm's Law Calculator
Calculate Voltage, current or resistance using Ohm's Law
