Knowing the current lets you choose cables, fuses and breakers. A 2 kW heater on 230 V draws about 8.7 A; the same power on a 120 V circuit draws 16.7 A.
How to use the Watts to Amps Calculator
- Current type
- Power
- Voltage
- Power factor
Results update as you type, every field has its own unit menu, and everything is calculated in your browser.
How it works
Choose the system, enter the power, voltage and (for AC) power factor.
Inputs explained
| Field | What to enter |
|---|---|
| Current type | Choose one: DC, AC single-phase, AC three-phase (line-to-line voltage), AC three-phase (line-to-neutral voltage) |
| Power | Units: W, kW, MW, hp, mW |
| Voltage | Units: V, kV, mV |
| Power factor | A number |
Example values
How the main result changes when Power changes and everything else stays at the example values above:
| Power (W) | Current (A) |
|---|---|
| 1,000 | 4.3478 |
| 1,500 | 6.5217 |
| 2,000 | 8.6957 |
| 2,500 | 10.8696 |
| 3,000 | 13.0435 |
| 4,000 | 17.3913 |
Formula
DC: I = P/V · 1-phase: I = P/(V·PF) · 3-phase L-L: I = P/(√3·V·PF) · 3-phase L-N: I = P/(3·V·PF)
Worked example
Inputs — Current type: AC single-phase; Power: 2,000 W; Voltage: 230 V; Power factor: 1.
Results — Current = 8.69565 A.
Key terms
- Ampere
- SI unit of electric current.
Frequently asked questions
How many amps is 1,000 W at 230 V?
About 4.35 A.
How many amps is 1,000 W at 120 V?
About 8.33 A.
Why does power factor increase current?
Reactive current flows without delivering real power.
Which voltage should I use for three-phase?
Usually the line-to-line voltage (e.g. 400 V).