How to Convert watt to HP and HP to watt [Formulae with examples]

Watts and Horsepower are two power units. Watt is an electrical unit, whereas the HP is a mechanical unit. As an engineer/technician/electrician, you often encounter these two units and you might need to calculate current in motors or similar cases.

In such cases, you should know the conversion between watts and HP. Just use the equation below:

1 hp = 745.6 watts

Let's do an example of it.

Example: Convert 50 hp to watt

Solution: 50 hp = 50 * hp = 50 * 745.6 watt = 37285 watt

Another one for inverse:

Example: Convert 5000 watts to hp

Solution: 1 hp = 745.6 watts,

5000 * 1 hp = 5000 * 745.6 watts

5000 watt = 5000 * 1 hp / 745.6 = 6.70 hp

Let's consider a real-life case where you need it.

Example: Find the amp-size for a single phase 1/2 HP motor at 120 V having efficiency 80% and power factor 0.88

Solution: From formula: I = P / (V * PF * Effieiency)

The formula has power in watt units.

Now for applying it to our case

I = (1/2 * 745.6) / (120 * 0.8 * 0.88) = 4.41 A