Unit Converter

Continue in the tool

More pages for this tool

horsepower to watts

Horsepower to watts: hp, cv and PS

The tool opens converting 1 hp to watts. Change the source unit to cv, or the target to kW, to compare the US horsepower with the metric horsepower used on European and Brazilian spec sheets.

Two horses, two values

At least two "horses" are in use. Mechanical horsepower (hp), defined as 550 foot-pounds-force per second, equals 745.6999 W. Metric horsepower (cv in Portuguese, PS in German), defined as the power to lift 75 kgf by 1 m in 1 s, equals 735.49875 W. The gap is 1.4%: a "100 hp" engine delivers 74.57 kW, and a "100 cv" one delivers 73.55 kW. On Brazilian and European car spec sheets the unit is cv; in American material it is hp.
Electric motors mix the units. In Brazil, the nameplate of a three-phase motor usually lists power in cv and in kW, and sizing the drive or the cable requires kW. A 5 cv motor delivers 5 × 0.73549875 = 3.677 kW. A 5 hp motor in the US delivers 3.728 kW. In US electrical work there is also the "electrical horsepower", fixed at exactly 746 W; it is practically the mechanical hp and is used to calculate motor current.
Mind what the number measures. A car rating is the engine power at the crankshaft; what reaches the wheels is lower, usually 10% to 20% less because of the drivetrain. And "hp" on cheap vacuum and compressor motors is often a theoretical peak power that cannot be sustained in continuous use. To compare equipment, convert everything to kW and look at the rated continuous power, not the peak.

Power conversions

1 hp in watts

Input: 1 hp
Expected output: 745.6999 W

Mechanical horsepower.

1 cv in watts

Input: 1 cv
Expected output: 735.49875 W

Metric horsepower, 1.4% smaller.

A 5 cv motor

Input: 5 cv
Expected output: 3.6775 kW

The value to use when sizing the cable and the drive.

A 150 cv car

Input: 150 cv
Expected output: 110.3248 kW

In hp, the same 110.3 kW is 147.9 hp.

100 hp in kilowatts

Input: 100 hp
Expected output: 74.57 kW

A 100 hp motor delivers about 1 kW more than a 100 cv one.

Full tool FAQ

Which unit categories does the tool convert?

There are fourteen categories: length, mass, temperature, data, time, speed, area, pressure, volume, energy, power, angle, frequency and fuel economy. Each one holds several units, from nanometer to nautical mile, from bit to exbibyte, from pascal to atmosphere, and conversion only happens between units of the same kind, because turning meters into seconds makes no sense.

Can I see the value in every unit at the same time?

Why is converting temperature different from converting length?

What is the difference between MB and MiB (decimal vs binary)?

Why are L/100 km and km/L not just a different factor?

Can I type the conversion instead of using the selectors?

Is the data I type sent to any server?

How do I control rounding and scientific notation?

Frequently asked questions

Are cv and hp the same thing?

Nearly, but no. 1 hp is 745.7 W and 1 cv is 735.5 W, so the hp is 1.4% bigger. On spec sheets, the unit must be written next to the number.

How many watts is one horsepower?

It depends on the horse: 745.7 W for mechanical hp and 735.5 W for metric cv. In practice, one horsepower sits near 0.74 kW.

Can I use cv to work out an electricity bill?

First convert to kW and multiply by the hours of use to get kWh. The motor still draws more than it delivers because of efficiency, so divide the output power by the efficiency on the nameplate.

Next steps

From	To
1 hp	745.699872 W
2 hp	1,491.4 W
5 hp	3,728.499 W
10 hp	7,456.999 W
20 hp	14,913.997 W
50 hp	37,284.994 W
100 hp	74,569.987 W
1,000 hp	745,699.872 W

From

1 hp

745.699872 W

2 hp

1,491.4 W

5 hp

3,728.499 W

10 hp

7,456.999 W

20 hp

14,913.997 W

50 hp

37,284.994 W

100 hp

74,569.987 W

1,000 hp

745,699.872 W

Two horses, two values

At least two "horses" are in use. Mechanical horsepower (hp), defined as 550 foot-pounds-force per second, equals 745.6999 W. Metric horsepower (cv in Portuguese, PS in German), defined as the power to lift 75 kgf by 1 m in 1 s, equals 735.49875 W. The gap is 1.4%: a "100 hp" engine delivers 74.57 kW, and a "100 cv" one delivers 73.55 kW. On Brazilian and European car spec sheets the unit is cv; in American material it is hp.

Electric motors mix the units. In Brazil, the nameplate of a three-phase motor usually lists power in cv and in kW, and sizing the drive or the cable requires kW. A 5 cv motor delivers 5 × 0.73549875 = 3.677 kW. A 5 hp motor in the US delivers 3.728 kW. In US electrical work there is also the "electrical horsepower", fixed at exactly 746 W; it is practically the mechanical hp and is used to calculate motor current.

Mind what the number measures. A car rating is the engine power at the crankshaft; what reaches the wheels is lower, usually 10% to 20% less because of the drivetrain. And "hp" on cheap vacuum and compressor motors is often a theoretical peak power that cannot be sustained in continuous use. To compare equipment, convert everything to kW and look at the rated continuous power, not the peak.

Power conversions

1 hp in watts

Input: 1 hp
Expected output: 745.6999 W

Mechanical horsepower.

1 cv in watts

Input: 1 cv
Expected output: 735.49875 W

Metric horsepower, 1.4% smaller.

A 5 cv motor

Input: 5 cv
Expected output: 3.6775 kW

The value to use when sizing the cable and the drive.

A 150 cv car

Input: 150 cv
Expected output: 110.3248 kW

In hp, the same 110.3 kW is 147.9 hp.

100 hp in kilowatts

Input: 100 hp
Expected output: 74.57 kW

A 100 hp motor delivers about 1 kW more than a 100 cv one.

Full tool FAQ

Which unit categories does the tool convert?

Can I see the value in every unit at the same time?

Why is converting temperature different from converting length?

What is the difference between MB and MiB (decimal vs binary)?

Why are L/100 km and km/L not just a different factor?

Can I type the conversion instead of using the selectors?

Is the data I type sent to any server?

How do I control rounding and scientific notation?

Frequently asked questions

Are cv and hp the same thing?

Nearly, but no. 1 hp is 745.7 W and 1 cv is 735.5 W, so the hp is 1.4% bigger. On spec sheets, the unit must be written next to the number.

How many watts is one horsepower?

It depends on the horse: 745.7 W for mechanical hp and 735.5 W for metric cv. In practice, one horsepower sits near 0.74 kW.

Can I use cv to work out an electricity bill?

First convert to kW and multiply by the hours of use to get kWh. The motor still draws more than it delivers because of efficiency, so divide the output power by the efficiency on the nameplate.