Watts to horsepower

Multiply watts by 0.00134102 to get horsepower.

1 W = 0.00134102 hpNIST SP 811

Convert

1.341hp

1,000 W = 1.341 hp

How to convert watts to horsepower

The horsepower is mechanical (imperial) horsepower, about 745.70 watts. The watt is the SI unit of power, one joule per second.

Worked example — 1,000 W: 1,000 × 0.00134102 = 1.341 hp.

Watts to horsepower table

Common conversions. The reverse table is on horsepower to watts.
Watts	Horsepower
100 W	0.134102 hp
250 W	0.335256 hp
500 W	0.670511 hp
745.7 W	1 hp
1,000 W	1.341 hp
2,000 W	2.682 hp
5,000 W	6.7051 hp
10,000 W	13.4102 hp
100,000 W	134.1022 hp

Reverse and related

horsepower → wattsreverse conversion kW → hp1 kW = 1.341 hp hp → kW1 hp = 0.7457 kW kW → W1 kW = 1,000 W hp → PS1 hp = 1.0139 PS W → kW1 W = 0.001 kW BTU/h → kW1 BTU/h = 0.000293071 kW

About watts and horsepower

Watt (W)

1 W = 0.00134102 hp

Definition. The SI unit of power, one joule per second

History and origin

The watt is the SI unit of power, one joule per second, named after James Watt for his work on the steam engine. It measures the rate at which energy is used or produced.

Current use

Watts rate light bulbs, appliances and solar panels the world over.

Source: NIST SP 811, App. B (power). Mechanical hp = 550 ft·lbf/s ≈ 745.70 W; metric hp (PS) = 75 kgf·m/s = 735.49875 W

Horsepower (hp)

1 hp = 745.6999 W

Definition. Mechanical (imperial) horsepower, about 745.70 watts

History and origin

Horsepower was coined by James Watt in the 1780s to compare his steam engines to the draught horses they replaced, based on the work a horse could do. Mechanical horsepower is about 745.7 watts.

Current use

Horsepower rates car and engine power in the United States and United Kingdom.

Source: NIST SP 811, App. B (power). Mechanical hp = 550 ft·lbf/s ≈ 745.70 W; metric hp (PS) = 75 kgf·m/s = 735.49875 W

Where people use this

Watts: light bulbs, appliances, solar panels. Horsepower: car and engine power in the US/UK. 745.7 W is about 1 hp.

How we know this is right

The factor is fixed by the standards that define the units, not chosen — so it is exact, not a measurement:

1 hp = 745.6998716 W, so 1 W = 1 ÷ 745.6998716 = 0.00134102 hp.

Every value is carried to full double precision; the display is rounded.

Both units are defined in NIST SP 811, App. B (power). Mechanical hp = 550 ft·lbf/s ≈ 745.70 W; metric hp (PS) = 75 kgf·m/s = 735.49875 W.

Questions people ask

How many watts in a horsepower?

One mechanical horsepower is about 745.7 watts.

How many hp is 1000 W?

1000 W is about 1.34 hp.

How many hp is 500 W?

500 W is about 0.67 hp.

All watt conversions

Kilowatts to watts1 kW = 1,000 W Horsepower to watts1 hp = 745.6999 W Watts to kilowatts1 W = 0.001 kW