Watts to Horsepower Conversion (W to hp)

How to Convert Watts to Horsepower

To convert a watt measurement to horsepower, use one of the formulas below.

Watts to Mechanical Horsepower

Formula to convert watts to mechanical horsepower:

hp(I) = watts ÷ 745.699872

Since mechanical horsepower is equal to 745.699872 watts, the formula to find mechanical horsepower is the power in watts divided by 745.699872.

For example, here's how to convert 5,000 watts to mechanical horsepower.

5,000 W = (5,000 ÷ 745.699872) = 6.70511 hp(I)

Watts to Electric Horsepower

Formula to convert watts to electric horsepower:

hp(E) = watts ÷ 746

Since electric horsepower is equal to 746 watts, the formula to find electric horsepower is the power in watts divided by 746.

For example, here's how to convert 5,000 watts to electric horsepower.

5,000 W = (5,000 ÷ 746) = 6.702413 hp(E)

Watts to Metric Horsepower

Formula to convert watts to metric horsepower:

hp(M) = watts ÷ 735.49875

Since metric horsepower is equal to 735.49875 watts, the formula to find metric horsepower is the power in watts divided by 735.49875.

For example, here's how to convert 5,000 watts to metric horsepower.

5,000 W = (5,000 ÷ 735.49875) = 6.798108 hp(M)

Watts to Boiler Horsepower

Formula to convert watts to boiler horsepower:

hp(S) = watts ÷ 9,809.5

Since boiler horsepower is equal to 9,809.5 watts, the formula to find boiler horsepower is the power in watts divided by 9,809.5.

For example, here's how to convert 5,000 watts to boiler horsepower.

5,000 W = (5,000 ÷ 9,809.5) = 0.50971 hp(S)

Watts and horsepower are both units used to measure power. Keep reading to learn more about each unit of measure.

Watts

One watt is the power equal to the rate of energy of one joule per second in an electrical circuit.^[1] One watt is also equal to the power produced in a circuit with a voltage potential of one volt with a current of one amp.

The watt is the SI derived unit for power in the metric system. Watts can be abbreviated as W; for example, 1 watt can be written as 1 W.

Watt's Law states the relationship between power, current, and voltage. Using Watt's Law, it's possible to express the power in watts as an expression using current and voltage.

P_W = I_A × V_V

The power in watts is equal to the current in amperes times the potential difference in volts.

Combining this with Ohm's Law, it's also possible to express the power in watts using resistance in addition to volts and amps.

Horsepower

Electric and mechanical are the most commonly used types. One electric horsepower is equivalent to 746 watts and one mechanical horsepower is equivalent to 745.699872 watts.

Mechanical Horsepower

Mechanical horsepower is often used to measure the output of engines and motors in North America. One mechanical horsepower is equal to 745.69987158227022 watts.

The mechanical horsepower is a US customary and imperial unit of power. Mechanical horsepower can be abbreviated as hp(I); for example, 1 mechanical horsepower can be written as 1 hp(I).

Electric Horsepower

Electric horsepower is used to measure the output of electric motors and other electrical machines in the US. One electric horsepower is equal to exactly 746 watts.

The electric horsepower is a US customary and imperial unit of power. Electric horsepower can be abbreviated as hp(E); for example, 1 electric horsepower can be written as 1 hp(E).

Metric Horsepower

One metric horsepower is the power needed to one metric horsepower as the lift a 75 kilogram mass at at one meter per second.^[2] One metric horsepower is equal to 735.49875 watts.

The metric horsepower is a non-SI metric unit for power. Metric horsepower can be abbreviated as hp(M), and are also sometimes abbreviated as PS, cv, hk, pk, ks, or ch. For example, 1 metric horsepower can be written as 1 hp(M), 1 PS, 1 cv, 1 hk, 1 pk, 1 ks, or 1 ch.

Boiler Horsepower

Boiler horsepower is used to measure the power of a boiler to generate steam. One boiler horsepower is equal to the power needed to evaporate 34.5 pounds in one hour.^[3]

Boiler horsepower can be abbreviated as hp(S); for example, 1 boiler horsepower can be written as 1 hp(S).

The term horsepower was adopted by Scottish inventor James Watt to measure the power output of his steam engine and to compare that power with that of horses horses.^[4] Horsepower were later used to measure the power output of piston and turbine engines and electrical motors.

Try our engine horsepower calculator to calculate the power of a motor.

Watts	Mechanical Horsepower	Electric Horsepower	Metric Horsepower	Boiler Horsepower
1 W	0.001341	0.00134	0.00136	0.000102
2 W	0.002682	0.002681	0.002719	0.000204
3 W	0.004023	0.004021	0.004079	0.000306
4 W	0.005364	0.005362	0.005438	0.000408
5 W	0.006705	0.006702	0.006798	0.00051
6 W	0.008046	0.008043	0.008158	0.000612
7 W	0.009387	0.009383	0.009517	0.000714
8 W	0.010728	0.010724	0.010877	0.000816
9 W	0.012069	0.012064	0.012237	0.000917
10 W	0.01341	0.013405	0.013596	0.001019
20 W	0.02682	0.02681	0.027192	0.002039
30 W	0.040231	0.040214	0.040789	0.003058
40 W	0.053641	0.053619	0.054385	0.004078
50 W	0.067051	0.067024	0.067981	0.005097
60 W	0.080461	0.080429	0.081577	0.006117
70 W	0.093872	0.093834	0.095174	0.007136
80 W	0.107282	0.107239	0.10877	0.008155
90 W	0.120692	0.120643	0.122366	0.009175
100 W	0.134102	0.134048	0.135962	0.010194
200 W	0.268204	0.268097	0.271924	0.020388
300 W	0.402307	0.402145	0.407886	0.030583
400 W	0.536409	0.536193	0.543849	0.040777
500 W	0.670511	0.670241	0.679811	0.050971
600 W	0.804613	0.80429	0.815773	0.061165
700 W	0.938715	0.938338	0.951735	0.071359
800 W	1.0728	1.0724	1.0877	0.081554
900 W	1.2069	1.2064	1.2237	0.091748
1000 W	1.341	1.3405	1.3596	0.101942

Watts to Horsepower Converter

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