What is a Power & Horsepower Converter?
The power converter switches between W, kW, HP (horsepower), and PS.
How it's calculated
1 HP (mechanical) = 745.7 W, 1 PS (metric) = 735.5 W, 1 kW ≈ 1.36 PS
Units that are easy to mix up
| Units | Why it's confusing | How to tell them apart |
|---|---|---|
| HP vs PS | Both translate to "horsepower" | 1 HP = 745.7W (mechanical), 1 PS = 735.5W (metric) — about 1.4% apart |
| kW vs kWh | Power vs energy confusion | kW is instantaneous power; kWh is that power sustained for one hour (the billing unit) |
Where did horsepower come from?
James Watt coined the unit while selling steam engines, because his customers understood work in terms of how many horses it would take. He observed horses turning a mill wheel to pump water from a mine, and defined 1 horsepower as the sustained work rate of a single horse.
The two variants of horsepower — HP (745.7 W) and PS (735.5 W) — differ by about 1.4%, which is why the same engine can be advertised as 300 HP or 304 PS depending on region.
Good to know
- A real horse can exceed 1 horsepower — some measurements show a horse can burst up to 15 HP momentarily. Watt's definition captured sustainable output, with margin built in for selling engines confidently.
- A person can sustain only about 0.1 horsepower continuously — a useful anchor for grasping how strong a 100-horsepower car really is.
- Watts (W) and watt-hours (Wh) are different things — W is instantaneous power, Wh is that power sustained over time. Electricity bills are based on kWh.
- An air conditioner's power consumption and cooling capacity are both measured in kW but mean different things — the ratio between them is the COP (coefficient of performance).
- Electric vehicles standardize on kW for power output. 150 kW is roughly 204 PS.
Frequently asked questions
Q. Which is bigger, HP or PS?
HP is slightly larger. 1 HP = 745.7 W versus 1 PS = 735.5 W, about a 1.4% difference.
Q. How many horsepower is 1 kW?
About 1.36 PS or 1.34 HP.
Q. Which matters more, horsepower or torque?
It depends on the application. Torque affects acceleration and towing power more, while horsepower affects top speed more.