kW to amps calculator
Convert between amps, kW, kVA and horsepower for 230 V single phase, 400 V three phase or DC. Type what you know and the rest is worked out, with the working shown.
Convert a load
No sign-up. Works offline, nothing is uploaded, and the working is shown.
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What it does
- Any way round: start from amps, kW, kVA or horsepower and get the others.
- Single phase, three phase or DC: with Australian voltages filled in and easy to change.
- Power factor and kVAr: for motors, air con and other loads that draw more current than their kW suggests.
- Horsepower with motor efficiency: from a motor’s rated output to the current it draws.
- Common loads table: amps for kettles, hot water, ovens, cooktops, air con, pool pumps and EV chargers at single and three phase.
- Shows the working: each step of the sum, so you can check it or explain it to a client.
- A load list: add loads from the converter or the common loads table, put each on L1, L2, L3 or all three phases, and see the current on each phase against the supply rating, with warnings for overloaded or uneven phases. Handy before adding an EV charger or air con.
- A report for the job file: your logo, business and licence number, the conversion and working, the load list and current per phase, the method and a sign-off line. Or copy a short summary into a quote or email.
kW to amps at a glance
| Load | 230 V single phase | 400 V three phase (per phase) |
|---|---|---|
| 1 kW | 4.3 A | 1.4 A |
| 2.4 kW (kettle) | 10.4 A | 3.5 A |
| 3.6 kW (hot water) | 15.7 A | 5.2 A |
| 7.4 kW (EV charger) | 32.2 A | 10.7 A |
| 11 kW | 47.8 A | 15.9 A |
| 22 kW | 95.7 A | 31.8 A |
At a power factor of 1. A lower power factor means more current for the same kW.
The formulas
- Single phase: A = kW × 1000 ÷ (V × PF), and kVA = V × A ÷ 1000.
- Three phase: A = kW × 1000 ÷ (√3 × V × PF), and kVA = √3 × V × A ÷ 1000, with V between phases.
- DC: A = kW × 1000 ÷ V.
- Horsepower: kW in = hp × 0.7457 ÷ efficiency.
Common questions
How do I convert kW to amps?
Single phase: amps = kW × 1000 ÷ (volts × power factor). Three phase: amps = kW × 1000 ÷ (√3 × volts between phases × power factor). On 230 V with a power factor of 1, each kW is about 4.35 A.
How many amps is 7.4 kW?
About 32 A on 230 V single phase, which is why a 7.4 kW EV charger needs a 32 A circuit. An 11 kW charger on 400 V three phase draws about 16 A per phase.
What’s the difference between kW and kVA?
kVA is the apparent power, volts × amps. kW is the real power that does the work: kVA × power factor. For heaters, kettles and hot water the power factor is about 1, so kW and kVA are the same. Motors and some electronics have a lower power factor, so they draw more current for the same kW.
What voltage should I use in Australia?
230 V for single phase and 400 V between phases for three phase. Older equipment may say 240 V or 415 V. DC is for batteries, solar strings and vehicles.
How do I convert horsepower to amps?
Horsepower is a motor’s output. Input kW = hp × 0.7457 ÷ efficiency, then convert kW to amps with the power factor. Use the motor’s nameplate current where you have it, and remember motors draw several times more when starting.
Can it tell me if the supply can take another load?
The load list adds up the current on each phase from the loads you enter and compares it with the supply rating. That’s the connected load: the maximum demand worked out under AS/NZS 3000 (Appendix C) is usually lower, so use it as a first check, not the final answer.
Is anything uploaded?
No. It all runs in your browser, works offline once open, and remembers your last conversion on your device.
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