Convert horsepower to kilowatts. Multiply by 0.7457, with car engine tables and the metric horsepower compared side by side.

The formula

kilowatts = hp × 0.7456998716

Mechanical horsepower is defined as 550 foot-pounds-force per second. The foot, the pound and standard gravity are all exactly defined, so the watt equivalent — 745.6998715822702 W — is exact, and only its decimal presentation is rounded.

To go the other way, multiply by 1.34102209. See kW to hp.

Which horsepower

This page converts mechanical horsepower, the UK and US unit. Metric horsepower (PS) is 1.4% smaller:

hp	kW	in PS
100 hp	74.57 kW	101.4 PS
150 hp	111.85 kW	152.1 PS
200 hp	149.14 kW	202.8 PS
300 hp	223.71 kW	304.2 PS
500 hp	372.85 kW	506.9 PS

See PS to hp for the metric unit.

Quick reference

hp	kW
1 hp	0.746 kW
1.341 hp	1 kW
10 hp	7.46 kW
50 hp	37.28 kW
100 hp	74.57 kW
250 hp	186.42 kW
1000 hp	745.70 kW

Car engines

Kilowatts are the legal unit on European type approval documents, so a car’s registration paperwork gives kW while its advertising gives horsepower:

Class	hp	kW
City car	70 hp	52 kW
Small hatchback	110 hp	82 kW
Family saloon	150 hp	112 kW
Warm hatch	200 hp	149 kW
Performance saloon	300 hp	224 kW
Sports car	450 hp	336 kW
Supercar	700 hp	522 kW

Electric cars are usually specified in kW first and converted outward, which is the reverse of the combustion convention — a 150 kW motor is 201 hp.

Marine and industrial

	hp	kW
Outboard, small	15 hp	11.2 kW
Outboard, large	300 hp	223.7 kW
Tractor, compact	25 hp	18.6 kW
Tractor, field	150 hp	111.9 kW
Locomotive	4000 hp	2983 kW

Estimating in your head

Multiply by 3 and divide by 4. 200 hp × 3 is 600, ÷ 4 is 150 kW — the true answer is 149.1. That is within 0.6% and needs no decimals at all.

Horsepower to kilowatts