Convert Horsepower to Watts

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:

• 10 hp × 745.7 = 7,457 W

For electric motors, power is often shown in kilowatts (kW). Convert first, or use the direct link:

• 1 kW = 1,000 W
• 1 hp = 0.7457 kW (mechanical hp)

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.

How many watts are in 1 horsepower?

It depends on the horsepower type.

• Mechanical horsepower (hp): 1 hp = 745.699872 watts (often rounded to 746 W)
• Metric horsepower (PS): 1 PS = 735.49875 watts (often rounded to 735.5 W)
• Electric horsepower: 1 electric hp = 746 watts

What’s the formula to convert horsepower to watts?

Use this basic formula:

Watts = Horsepower × 745.699872 (for mechanical horsepower)

If you use metric horsepower (PS), use:

Watts = PS × 735.49875

How do you convert watts to horsepower?

Divide watts by the right constant:

• Mechanical horsepower (hp): hp = watts ÷ 745.699872
• Metric horsepower (PS): PS = watts ÷ 735.49875

Why do some sources say 746 watts per horsepower?

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.

What’s the difference between horsepower (hp) and metric horsepower (PS)?

They measure power, but they use different standards.

• Mechanical horsepower (hp): about 745.7 W
• Metric horsepower (PS): about 735.5 W

Metric horsepower is about 1.4% smaller than mechanical horsepower.

Is kilowatts the same as watts when converting from horsepower?

Kilowatts and watts measure the same thing, just in different sizes.

• 1 kW = 1,000 W
  To convert horsepower to kilowatts (mechanical hp):
  kW = hp × 0.745699872

How many watts is 5 horsepower?

Using mechanical horsepower:

5 hp × 745.699872 = 3,728.49936 W
That’s about 3,728.5 W, or about 3.73 kW.

How many watts is 10 horsepower?

Using mechanical horsepower:

10 hp × 745.699872 = 7,456.99872 W
That’s about 7,457 W, or about 7.46 kW.

How many watts is 100 horsepower?

Using mechanical horsepower:

100 hp × 745.699872 = 74,569.9872 W
That’s about 74,570 W, or about 74.57 kW.

Does horsepower measure the same thing as watts?

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.

Which horsepower standard should I use for motor power?

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%.

Can I convert horsepower to watts for electrical power use?

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).

How do I estimate electrical watts from horsepower for a motor?

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.

What does “hp” mean on equipment labels?

“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.

Why are my results slightly different from another conversion?

Small differences come from:

• Using hp vs PS vs electric hp
• Rounding (746 vs 745.699872)
• Mixing output horsepower with input electrical watts
• Nameplate ratings that assume certain test limits

What’s a quick horsepower to watts conversion rule?

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.