Watts to Horsepower Converter

746 watts make one mechanical horsepower and 735.5 make one metric — convert both, side by side.

Conversion table

Power	In horsepower
10	0.01341 HP
25	0.033526 HP
50	0.067051 HP
75	0.10058 HP
100	0.1341 HP
150	0.20115 HP
200	0.2682 HP
250	0.33526 HP
300	0.40231 HP
400	0.53641 HP
500	0.67051 HP
600	0.80461 HP
750	1.0058 HP
1,000	1.341 HP
1,500	2.0115 HP

🐎 Both horsepowers

1 hp (mechanical)745.7 W
1 PS / CV (metric)735.5 W
1 kW1.341 hp = 1.360 PS
100 hp74.6 kW = 101.4 PS

Comparing two spec sheets

Check which horsepower a figure uses before comparing. The metric one is 1.4% smaller, so the same engine gains about one and a half units crossing the Atlantic.
Metric horsepower goes by many names for the same 735.5 W: PS in Germany, CV in France and Spain, cv in Brazil, pk in the Netherlands, ch in French-speaking countries.
Kilowatts settle the argument, which is why European type approval quotes kW first and the horsepower figure in brackets.
Peak power is a single point on a curve. Two engines with identical horsepower can feel completely different if their torque arrives at different revs.

Where the horsepower came from

James Watt needed a way to sell steam engines to people who owned horses, so he measured what a dray horse could do turning a mill wheel and settled on 33,000 foot-pounds per minute. Converted to SI, that is 745.7 watts, and it is still the definition of mechanical horsepower today. The unit was invented for a sales pitch rather than for physics, which is exactly why it survived: it let a buyer picture the machine in terms he already understood. The watt, named after the same man, is the SI unit and needs no such translation — one watt is one joule per second.

Mechanical horsepower versus metric horsepower

Continental Europe defined its own horse. Instead of 33,000 foot-pounds per minute, it used 75 kilogram-force metres per second, which comes to 735.5 watts — about 1.4% less than the imperial figure. That unit is written PS in German, CV in French and Spanish, cv in Portuguese, pk in Dutch, and all of them mean the same 735.5 W. The gap is small but not negligible: a 200 hp car is 202.8 PS, and a manufacturer quoting the larger number is not exaggerating, just using the other definition. Kilowatts are the only figure that means the same thing everywhere.

Reading power on a spec sheet

European registration documents quote engine power in kW; the horsepower figure beside it is a courtesy conversion.
A figure written "150 PS (110 kW)" is metric; "150 hp (112 kW)" is mechanical. The kilowatts tell you which.
Electric motors are almost always rated in kW, even in markets that quote combustion engines in horsepower.
Appliance and tool ratings in horsepower are usually input power, not output at the shaft, so the useful power is lower.
Boiler horsepower is a completely different unit, 9,809.5 W, used only for steam boilers.
Some audio and pump equipment quotes "peak horsepower", a marketing figure the device cannot sustain.

A sense of scale

A person working steadily produces about 75 W; a trained cyclist can hold 250–400 W for an hour.
An electric kettle draws around 2,000 W, which is 2.7 hp — more than a small outboard motor.
A domestic washing machine motor: 400–800 W, under one horsepower.
A compact family car: 80–110 kW, which is 107–148 hp or 109–150 PS.
A modern diesel locomotive: 3,000–4,500 kW, some 4,000–6,000 hp.
A large wind turbine at rated output: 3–6 MW, that is 4,000–8,000 hp of electricity.

Worked examples

Both horsepowers, both directions

A 110 kW engine

110,000 W ÷ 745.7 = 147.5 hp
110,000 W ÷ 735.5 = 149.6 PS
The same engine, two legitimate numbers

110 kW = 147.5 hp = 149.6 PS

A 5 hp workshop motor

5 × 745.7 = 3,728 W
3,728 W = 3.73 kW
In metric horsepower: 3,728 ÷ 735.5 = 5.07 PS

5 hp = 3.73 kW = 5.07 PS

Frequently Asked Questions

How many watts are in one horsepower?

745.7 watts for mechanical horsepower, the imperial unit used in Britain and the United States. Metric horsepower — PS, CV, cv, pk — is 735.5 watts. The 1.4% gap between them is why the same engine can be advertised with two different numbers, both honest.

What is the difference between hp and PS?

They are two definitions of the same idea. Mechanical horsepower is 33,000 foot-pounds per minute, or 745.7 W. Metric horsepower is 75 kilogram-force metres per second, or 735.5 W. PS is therefore slightly smaller, so a 150 hp engine is 152.1 PS. Kilowatts avoid the ambiguity entirely.

How do I convert kW to hp?

Multiply kilowatts by 1.341 for mechanical horsepower, or by 1.360 for metric. So 100 kW is 134.1 hp or 136.0 PS. To go the other way, multiply hp by 0.7457 to get kilowatts.

Why do European cars list power in kW?

Because kW is the SI unit and the only one that means the same thing in every market, so European type approval requires it. The horsepower figure printed beside it is a convenience for buyers, and it is usually metric horsepower rather than the imperial kind.

Is a 2000 W kettle really more powerful than a small motorbike engine?

In power terms, yes: 2,000 W is 2.7 hp, more than a 50 cc scooter engine produces. What differs is what the power is for. The kettle converts electricity into heat with almost no loss, while an engine has to overcome friction and deliver its power through a gearbox to move a mass.

What is boiler horsepower?

A separate unit worth 9,809.5 watts, roughly thirteen times a mechanical horsepower, defined by the steam a boiler can raise rather than by mechanical work. It appears only in steam plant specifications, but it explains the occasional spec sheet where a horsepower figure looks impossibly small.