Watts to Amps Calculator
Convert watts to amps free — enter power, voltage and power factor for DC, single or three-phase AC. 1,000W at 230V (PF 0.9) draws 4.83A.
About the Watts to Amps Calculator
This free watts to amps calculator finds the current a load draws: I = P ÷ V for DC, I = P ÷ (V × PF) for single-phase AC and I = P ÷ (V × PF × √3) for three-phase. Enter the wattage from an appliance label, set your voltage, and amps appear instantly.
Use it to size breakers, fuses, cables, UPS units and solar inverters: a 1,500 W air conditioner at 230 V and PF 0.9 draws 7.25 A, a 2,000 W water heater pulls 8.7 A, and a 3,000 W generator can supply about 14.5 A. The same appliance at US 120 V draws nearly twice the current — which is why voltage matters as much as wattage.
A live table converts common appliance wattages (100–5,000 W) at your chosen voltage and power factor.
How to Use the Watts to Amps Calculator
- 1Enter the power in watts from the appliance label.
- 2Set your voltage (230 V default; 120 V for US) and choose DC, single-phase or three-phase.
- 3Adjust the power factor for AC loads (0.9 default).
- 4Read the current in amps and compare against your breaker rating.
Frequently Asked Questions
How many amps is 1000 watts at 230 volts?
At power factor 1, 1,000 ÷ 230 = 4.35 A; at the typical 0.9 PF it's 1,000 ÷ (230 × 0.9) = 4.83 A. At 120 V the same 1,000 W draws 8.33 A (PF 1) or 9.26 A (PF 0.9) — nearly double.
What is the watts to amps formula?
DC: amps = watts ÷ volts. Single-phase AC: amps = watts ÷ (volts × PF). Three-phase AC: amps = watts ÷ (volts × PF × 1.732). Lower power factors mean more current for the same real power.
How many amps does a 1500 watt AC draw?
A 1,500 W (about 1-ton inverter) air conditioner at 230 V with PF 0.9 draws roughly 7.25 A. Its startup surge can be 2–3× higher, so it's typically wired to a dedicated 16–20 A breaker.
How many watts can a 20 amp breaker handle?
At 230 V, up to 4,600 W continuous (20 × 230, PF 1) — though electricians size loads to 80%, about 3,680 W. At 120 V the ceiling is 2,400 W with a practical limit near 1,920 W.
Why does my UPS or inverter rating use VA instead of watts?
VA (volt-amperes) is apparent power: VA = volts × amps regardless of power factor, while watts = VA × PF. A 1,000 VA UPS at PF 0.8 delivers only 800 W of real power — divide your wattage by the PF when sizing.