How to convert watts to amps
- Choose the direction: watts to amps, or amps to watts.
- Choose the circuit: DC (batteries, solar panels, car and RV wiring), single-phase AC (household outlets) or three-phase AC (motors, workshops and commercial buildings).
- Enter the power or the current and the voltage. Use the nameplate or label of the appliance. For three-phase, enter the line-to-line voltage.
- Set the power factor for AC loads. It is 1 for purely resistive loads such as heaters, kettles and incandescent bulbs, and lower for motors, compressors and some power supplies.
You get the current, the apparent power in volt-amperes and the power in kilowatts, the formula with your numbers, and a table of the same load at other common voltages.
Watts to amps formulas
| Circuit | Watts to amps | Amps to watts |
|---|---|---|
| DC | I = P ÷ V | P = V × I |
| AC single-phase | I = P ÷ (V × PF) | P = V × I × PF |
| AC three-phase | I = P ÷ (√3 × VL-L × PF) | P = √3 × VL-L × I × PF |
P is the real power in watts, V the voltage, I the current in amperes and PF the power factor (cos φ). √3 ≈ 1.732 appears in three-phase circuits because the line-to-line voltage is √3 times the voltage of each phase to neutral. If you only know the line-to-neutral voltage of a three-phase supply, use I = P ÷ (3 × VL-N × PF), which gives the same answer.
Worked examples
- 1,500 W space heater on 120 V: I = 1,500 ÷ 120 = 12.5 A. That fits a 15 A circuit, but a load that runs for three hours or more counts as a continuous load under the NEC and should stay at or below 80% of the breaker rating — 12 A on a 15 A circuit.
- 2,000 W kettle on 230 V: I = 2,000 ÷ 230 = 8.7 A.
- 10 kW three-phase motor at 400 V, PF 0.85: I = 10,000 ÷ (1.732 × 400 × 0.85) = 16.98 A per line. The apparent power is 10,000 ÷ 0.85 = 11,765 VA, and that, not the 10 kW, is what the supply cable has to carry.
- Amps to watts, 12 V DC: a 5 A fridge in a camper uses 12 × 5 = 60 W.
Common household voltages
The same appliance draws a different current depending on where you live. Nominal mains voltages:
| Region | Single-phase | Three-phase (line-to-line) |
|---|---|---|
| United States, Canada | 120 V (240 V for dryers, ranges, EV chargers) | 208 V or 480 V |
| Europe, UK, Australia, most of Asia and Africa | 230 V | 400 V |
| Saudi Arabia, Iraq, Egypt and much of the Arab world | 220–230 V (127 V in older Saudi buildings) | 380–400 V |
| Japan | 100 V (200 V for large appliances) | 200 V |
| Cars, trucks, RVs and solar systems | 12 V, 24 V or 48 V DC | |
Real power, apparent power and power factor
In AC circuits with motors or coils, current and voltage are out of step, so part of the current does no useful work. The real power (watts) is what turns into heat, light or motion and what your meter bills; the apparent power (volt-amperes, VA) is volts times amps and decides how large cables, fuses and generators must be. The ratio of the two is the power factor. A motor rated 10 kW at PF 0.85 takes as much current as a 11.8 kW heater.
The converter gives the running current. Motors draw several times that when they start, and wire sizing and breaker selection follow code tables (NEC Article 310 and 430 in the U.S., IEC 60364 in most other countries) — the voltage drop calculator checks whether a cable is long enough to matter. Have mains work done by a qualified electrician.
Frequently asked questions
How many amps is 1,500 watts?
At 120 V, 1,500 W is 12.5 A. At 230 V it is 6.5 A, and at 240 V it is 6.25 A — for a resistive load such as a heater with a power factor of 1.
How do I convert amps to watts?
Multiply amps by volts (and by the power factor for AC motors): P = V × I × PF. 10 A at 230 V with PF 1 is 2,300 W. For three-phase, multiply by √3 as well.
Can you convert watts to amps without the voltage?
No. Watts are volts times amps, so the same power means twice the current at half the voltage. A 60 W load draws 5 A at 12 V but only 0.5 A at 120 V.
How many amps does a 3-phase 10 kW load draw?
At 400 V and a power factor of 0.85 it draws about 17 A per line (10,000 ÷ (1.732 × 400 × 0.85)). At 480 V and PF 0.9 it is about 13.4 A.
What power factor should I use?
Use the value on the nameplate. Without it, 1 is right for heaters and incandescent lamps, about 0.85 is a reasonable estimate for induction motors at full load, and modern electronics with power factor correction are close to 0.95–1.
Last updated: October 19, 2026