watts to horsepower (hp) Converter
Convert watts to horsepower (hp) instantly. Includes a reference table and formula.
| watts | horsepower (hp) |
|---|
How to convert watts to horsepower (hp)
Enter your value
Type the number of watts you want to convert into the left box. The result in horsepower (hp) appears instantly in the right box. You can also type into the right box to convert in the other direction.
Use the swap button
Click the ⇄ Swap button to reverse the conversion — horsepower (hp) to watts. Your current value carries across so you don't have to re-enter anything.
About watts and horsepower (hp)
The watt is the modern SI unit of power, defined precisely from joules per second, while horsepower is a historical unit James Watt devised in the 1780s to compare his steam engines against the mill horses they replaced. The conversion factor (745.7 watts per horsepower) preserves that 18th-century calculation, which is why it isn't a clean round number.
Watts and horsepower in engines, motors, and everyday electronics
Comparing car specs across regions
US and UK car specifications typically list power in horsepower, while many European manufacturers list metric horsepower (PS) — a slightly smaller unit at 735.5 watts versus 745.7 watts for mechanical horsepower. Converting to watts gives a unit-agnostic way to compare engine outputs across regions without the ~1.4% discrepancy between the two horsepower definitions causing confusion.
Electric vehicles bridge both worlds
Electric motors are naturally rated in kilowatts because that's how electrical power is measured, but EV marketing and comparisons to combustion vehicles often also quote horsepower for familiarity. A 150kW electric motor, for example, is roughly equivalent to 201 horsepower — EV spec sheets frequently list both figures side by side for this reason.
Putting engine power into everyday perspective
A modest 130hp compact car engine outputs about 97,000 watts — roughly the same instantaneous power as running 65 hair dryers simultaneously. This kind of comparison helps put abstract horsepower or wattage figures into a more intuitive, everyday context when explaining engine or motor specifications to a non-technical audience.
1 mechanical horsepower = 745.7 watts, originally calibrated by James Watt in 1782 based on the power output of a brewery horse hauling coal. Metric horsepower (PS, used in European car specs) is slightly different: 735.5 W.
| watts | horsepower (hp) |
|---|---|
| 100 | 0.1341 |
| 500 | 0.6705 |
| 1000 | 1.341 |
| 2000 | 2.682 |
| 5000 | 6.705 |
| 10000 | 13.41 |
Frequently asked questions
How do I convert watts to horsepower (hp)?
To convert watts to horsepower (hp), multiply by 0.00134102. Or use the calculator above for instant results.
How many horsepower (hp) are in 1 watt?
1 watt equals 0.00134102 horsepower (hp).
Why is 1 horsepower defined as 745.7 watts?
James Watt calculated mechanical horsepower in the 1780s from how much coal a mill horse could haul, so he could market his steam engines by comparing output to the horses they replaced. The modern figure preserves that 18th-century calculation almost exactly.
Is metric horsepower (PS) the same as mechanical horsepower?
No. Mechanical horsepower is 745.7 watts, while metric horsepower (PS in Europe) is 735.5 watts, about 1.4% smaller. A car rated at 300 PS has slightly less actual power than one rated at 300 mechanical hp.
Why do electric motors use watts while engines use horsepower?
Watts are the natural SI unit for anything measured electrically. Horsepower persists for combustion engines largely due to marketing history and consumer familiarity, even though watts would work equally well mathematically.
How many watts does a typical car engine produce?
A 130hp compact car engine is roughly 97,000 watts (97 kW), a 200hp sedan is about 149 kW, and a 500hp sports car is roughly 373 kW — far more than a household microwave's 1,000-1,500 watts.
Is the watts to horsepower (hp) converter free?
Yes, the watts to horsepower (hp) converter is completely free with no sign-up required, no downloads, and it works offline once the page has loaded.