This HP to kW calculator converts horsepower into kilowatts and back, covering all three horsepower definitions — mechanical (imperial), metric (PS/cv), and electrical. Whether you are reading a US engine spec, a European PS figure, or an electric motor nameplate, this tool gives the correct kilowatt equivalent.
HP to kW Formula
James Watt defined horsepower to compare his steam engines to draft horses. The modern mechanical horsepower equals exactly 745.6999 watts. Because the kilowatt is the SI unit of power used worldwide for electric motors, EVs, and generators, converting between HP and kW is one of the most common power calculations in both automotive and electrical work.
The Three Types of Horsepower
Not all horsepower is identical, and using the wrong one introduces small but real errors:
- Mechanical horsepower (hp): the US/UK standard. 1 hp = 0.7457 kW. Used for most engine and car specs.
- Metric horsepower (PS, cv, ch, pk): common in Europe and Japan. 1 PS = 0.7355 kW — slightly smaller, which is why a "147 kW" engine is marketed as 200 PS but only about 197 mechanical hp.
- Electrical horsepower: used for electric motors in North America. 1 electrical hp = 0.746 kW exactly.
HP to kW Conversion Table
| Horsepower (hp) | Kilowatts (kW) | Metric PS |
|---|---|---|
| 1 | 0.75 | 1.01 |
| 50 | 37.3 | 50.7 |
| 100 | 74.6 | 101.4 |
| 150 | 111.9 | 152.1 |
| 200 | 149.1 | 202.8 |
| 300 | 223.7 | 304.2 |
| 500 | 372.8 | 506.9 |
Worked Example
Going the other way, an electric motor rated 110 kW converts to 110 ÷ 0.7457 ≈ 147.5 hp. To convert torque-based figures instead, see the torque to kW calculator, or use HP to torque if you need pound-feet.
Conversions use exact published constants. Pick the correct horsepower type (mechanical, metric, or electrical) for your source figure to avoid a 1–2% discrepancy.
Frequently Asked Questions
No, but they both measure power. 1 kW is larger than 1 HP. 1 kW equals roughly 1.34 HP.
Metric horsepower (often written as PS, cv, or ch) is defined as the power required to lift 75 kilograms by 1 meter in 1 second. It equals 735.5 watts, slightly less than mechanical HP.
One mechanical horsepower equals 0.7457 kilowatts. Metric horsepower (PS) is slightly less at 0.7355 kW, and electrical horsepower is 0.746 kW.
kW is the official SI unit required on documents, while PS (metric horsepower) is the traditional figure buyers recognize, so manufacturers print both.
One kilowatt is larger than one horsepower — 1 kW equals about 1.341 HP. So a 100 kW motor is roughly 134 HP.