# Watts to Amps Calculator

URL: https://speedycalculator.com/calculators/physics/ohms-law-power/
Last updated: 2026-10-25

> The watts to amps calculator converts power to current for DC, single-phase AC or three-phase AC circuits, using the voltage and power factor. It helps size cables, fuses and breakers.

## Inputs

- Power (W, kW, hp, mW)
- Voltage (V, mV, kV)
- Circuit type
- Power factor

## Results

- Current

## Formula

```
DC: I = P ÷ V
Single-phase: I = P ÷ (V × PF)
Three-phase: I = P ÷ (√3 × V × PF)
```

## Explanation

Current depends on both power and voltage: the same appliance draws half the current at 240 V that it does at 120 V.

### How to use the Watts to Amps Calculator

- **Power**
- **Voltage**
- **Circuit type**
- **Power factor**

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Divide power by voltage, adjusted for power factor and for √3 in three-phase circuits.

### Inputs explained

FieldWhat to enterPowerUnits: W, kW, hp, mWVoltageUnits: V, mV, kVCircuit typeChoose one: DC or single-phase AC, Three-phase AC (line-to-line voltage)Power factorA number

### Example values

How the main result changes when **Power** changes and everything else stays at the example values above:

Power (W)Current (A)1,0004.351,5006.522,0008.72,50010.873,00013.044,00017.39

## Worked example

Inputs — Power: 2,000 W; Voltage: 230 V; Circuit type: DC or single-phase AC; Power factor: 1.

Results — **Current = 8.7 A**.

## FAQ

**What breaker size do I need?**
Choose one rated above the continuous current, following local electrical codes.

**What power factor should I use?**
1 for heaters; about 0.8–0.95 for motors.

**What formula does the Watts to Amps Calculator use?**
DC: I = P ÷ V.