# Horsepower to Amps Calculator

URL: https://speedycalculator.com/calculators/physics/hp-to-amps/
Last updated: 2026-10-30

> The horsepower to amps calculator finds the current drawn by an electric motor of a given horsepower on DC, single-phase or three-phase AC, including efficiency and power factor.

## Inputs

- Current type
- Power (hp, kW, W)
- Voltage (V, kV, mV)
- Efficiency (%)
- Power factor

## Results

- Current
- Electrical input power

## Formula

```
DC: I = P/(V·η) · 1-phase: I = P/(V·η·PF) · 3-phase: I = P/(√3·V·η·PF),  1 hp = 745.7 W
```

## Explanation

Motor nameplates often list power in horsepower. Converting to amps tells you which cable, breaker and supply you need. Efficiency and power factor increase the current above the simple P/V value.

### How to use the Horsepower to Amps Calculator

- **Current type**
- **Power**
- **Voltage**
- **Efficiency (%)**
- **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 current type, enter the horsepower, voltage, efficiency and (for AC) power factor.

### Inputs explained

FieldWhat to enterCurrent typeChoose one: DC, AC single-phase, AC three-phasePowerUnits: hp, kW, WVoltageUnits: V, kV, mVEfficiency (%)A numberPower factorA number

### Example values

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

Power (hp)Current (A)2.511.21863.7516.8279522.43726.2528.04657.533.65581044.8744

## Worked example

Inputs — Current type: AC single-phase; Power: 5 hp; Voltage: 230 V; Efficiency (%): 85; Power factor: 0.85.

Results — **Current = 22.43719 A**; Electrical input power = 4,386.46983 W.

## Key terms

- **Horsepower**: Unit of power, 745.7 W (mechanical).

## FAQ

**How many amps is a 1 hp motor at 230 V?**
About 4–5 A single-phase, depending on efficiency and PF.

**Why does three-phase need less current?**
Power is shared over three conductors.

**What is a mechanical horsepower?**
745.7 W.

**Should I size the breaker at this current?**
Motors have high starting currents; follow electrical codes.


## Sources

- [OpenStax – University Physics Volume 2](https://openstax.org/details/books/university-physics-volume-2)
- [The Engineering ToolBox](https://www.engineeringtoolbox.com/)