How many watts is one horsepower?

One mechanical (imperial) horsepower equals 745.6999 watts, defined as 550 foot-pounds-force per second. So a 100 hp engine is about 74,570 W or 74.57 kW.

How do I convert watts back to horsepower?

Divide the watts by 745.6999. For example, 10,000 W / 745.6999 = 13.41 hp. This converter does both directions.

Which horsepower does this use?

It uses mechanical (imperial) horsepower, the standard for engines and motors in the US and UK. Metric horsepower (PS) is slightly different at about 735.5 W and is not used here.

How do I get kilowatts from horsepower?

Convert to watts then divide by 1000, which works out to about 0.7457 kW per hp. So 150 hp is roughly 111.85 kW.

What is the difference between mechanical and metric horsepower?

Mechanical (imperial) horsepower is 745.7 W, based on 550 ft-lbf/s. Metric horsepower (PS, cheval-vapeur) is 735.5 W, based on 75 kgf-m/s. Car specs in Europe often quote PS, which is about 1.4% smaller.

Is my data sent anywhere?

No — the conversion runs entirely in your browser and nothing is uploaded to any server.

What is the Horsepower to Watts Converter?

Free horsepower to watts converter. Convert mechanical (imperial) horsepower to watts or watts back to hp using the exact factor 1 hp = 745.6999 W. Runs entirely in your browser — nothing is uploaded. It runs free in your browser on Gera Tools, with nothing uploaded.

Horsepower to Watts Converter

Name: Horsepower to Watts Converter
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

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Horsepower to watts — the exact conversion

One mechanical horsepower equals 745.6999 watts. This converter turns horsepower (hp) into watts (W) and back, using the precise definition of 745.69987158 W per horsepower. Mechanical horsepower is the figure quoted for car engines, pumps, and motors in the US and UK.

Why the definition produces that exact number

Mechanical horsepower was defined by James Watt in the late 18th century to help sell steam engines by comparing them to draught horses. The working definition settled on 550 foot-pounds-force per second. When you convert that to SI units:

1 foot = 0.3048 m
1 pound-force = 4.44822 N
550 ft-lbf/s = 550 × 0.3048 × 4.44822 = 745.69987158 W

The converter multiplies horsepower by this factor to get watts, or divides watts by it to get horsepower. To reach kilowatts, divide the watt result by 1,000 (since 1 kW = 1,000 W).

Mechanical vs metric horsepower — which applies to you?

Type	Value	Used for
Mechanical (imperial) hp	745.70 W	US/UK car engines, pumps, motors
Metric hp (PS, CV, ch, pk)	735.50 W	European car specs, DIN rating
Electrical hp	746.00 W (exact)	Electric motors in US standards
Boiler hp	9,810.66 W	Steam boilers

This converter uses mechanical horsepower. If a European car quotes power in PS (Pferdestärke) and you want watts, the metric figure is 735.5 W/PS — about 1.4% smaller. For most engineering and motor comparisons in the US and UK, mechanical hp is the right choice.

Quick reference table

Horsepower (hp)	Watts (W)	Kilowatts (kW)
1	745.70	0.746
5	3,728	3.73
50	37,285	37.29
100	74,570	74.57
200	149,140	149.14
300	223,710	223.71
500	372,850	372.85

Worked examples

Converting hp to watts: A 200 hp engine produces 200 × 745.6999 = 149,140 W = 149.14 kW.

Converting watts to hp: A 3 kW electric motor is 3,000 ÷ 745.6999 = 4.02 hp.

Comparing EV and combustion specs: A 300 kW electric motor is 300,000 ÷ 745.6999 ≈ 402 hp — which is why high-performance EVs routinely quote 400+ hp equivalents.

Common use cases

Automotive: Comparing engine output specifications across different international formats
Electric motors: Converting motor nameplates between US standard (hp) and SI (kW/W) specs
Generators and pumps: Sizing generator output against appliance wattage requirements
Solar and renewables: Checking whether a solar system’s peak output (in watts) matches a quoted horsepower rating for a pump or compressor it needs to drive