In 1 horsepower there are 745.699872 watts. Meanwhile in 1 watts there are 0.001341 horsepower. Keep reading to learn more about each unit of measure and how they are calculated. Or just use the Watts to Horsepower calculator above to convert any number.
* Values rounded to 6 decimal places for readability
To convert horsepower (hp) to watts (W), multiply the horsepower value by the correct hp-to-watts conversion factor.
Mechanical horsepower (US): 1 hp = 745.7 W
Formula: W = hp × 745.7
Metric horsepower (PS): 1 PS = 735.5 W
Formula: W = PS × 735.5
Example:
For electric motors, power is often shown in kilowatts (kW). Convert first, or use the direct link:
When comparing gas engines and electric motors, make sure you match the same horsepower type. Ratings like brake horsepower (bhp) measure engine output before drivetrain losses, while wheel horsepower (whp) is lower because it’s measured at the wheels.
It depends on the horsepower type.
Use this basic formula:
Watts = Horsepower × 745.699872 (for mechanical horsepower)
If you use metric horsepower (PS), use:
Watts = PS × 735.49875
Divide watts by the right constant:
Most people use mechanical horsepower, which equals 745.699872 W. Many charts round it to 746 W for easy math. The small difference won’t matter for quick estimates, but it can matter in strict specs.
They measure power, but they use different standards.
Metric horsepower is about 1.4% smaller than mechanical horsepower.
Kilowatts and watts measure the same thing, just in different sizes.
Using mechanical horsepower:
5 hp × 745.699872 = 3,728.49936 W
That’s about 3,728.5 W, or about 3.73 kW.
Using mechanical horsepower:
10 hp × 745.699872 = 7,456.99872 W
That’s about 7,457 W, or about 7.46 kW.
Using mechanical horsepower:
100 hp × 745.699872 = 74,569.9872 W
That’s about 74,570 W, or about 74.57 kW.
Yes. Both measure power, or how fast work gets done. Watts are the standard unit in the metric system. Horsepower is still common for engines, motors, and older spec sheets.
Check the label or manual. Many motor ratings use hp (mechanical) in the US. Many European specs use PS (metric horsepower) or kW. Using the wrong standard can shift the result by about 1.4%.
You can convert power units, but electrical input and mechanical output can differ. Motors lose power as heat and friction. If you want input watts, you also need efficiency (and sometimes power factor for AC motors).
A simple estimate uses efficiency:
Electrical watts ≈ (hp × 745.7) ÷ efficiency
Example: a 2 hp motor at 85% efficiency:
(2 × 745.7) ÷ 0.85 ≈ 1,754 W
Real results vary by load, motor type, and wiring.
“hp” stands for horsepower. On motors, it usually refers to mechanical output power at the rated load and speed. For accurate comparisons, also check voltage, amps, RPM, and duty rating.
Small differences come from:
For mechanical horsepower, a quick rule is:
Watts ≈ hp × 746
It’s close enough for most everyday uses. For precise work, use 745.699872 W per hp.
The Calculate Box tool to convert horsepower to watts uses the open source script Convert.js to convert units of measurement. To use this tool, simply type a horsepower value in the box and have it instantly converted to watts.