Kilowatts, PS, and imperial horsepower
Edit any field; the others stay in sync. Metric PS and mechanical hp are close but not identical — both are shown.
How this power converter works
What power ratings mean
Power is the rate of energy transfer — how quickly work is done. Vehicle brochures, motor nameplates, and generator specs often quote power in different historical units that still coexist:
- Kilowatt (kW) — SI unit equal to 1,000 watts. Preferred on modern electric motors and many European car specs.
- Imperial horsepower (hp) — the mechanical horsepower commonly used in US and UK marketing (≈ 745.7 W).
- Metric horsepower (PS / cv) — widely used in continental Europe for engines (exactly 735.49875 W by common metric definition).
PS and hp are close but not identical. Converting with the wrong horsepower definition produces a few percent of error — enough to confuse a datasheet comparison.
Conversion factors
This page links all three through watts using standard constants, then updates every field when you edit one:
- 1 hp (mechanical) = 745.6998715822702 W
- 1 PS (metric) = 735.49875 W
- 1 kW = 1,000 W
Worked example
An electric motor rated 75 kW is about 100.6 hp or 102.0 PS. A petrol engine advertised at 150 PS is roughly 148 hp or 110.3 kW. When manufacturers quote peak versus continuous power, use the same kind of rating on both sides of a comparison.
Power versus energy
Horsepower and kilowatts describe how hard a machine works at a moment in time. Kilowatt-hours describe how much energy was used over time. A 2 kW heater running for 3 hours uses 6 kWh of energy; that energy conversion belongs on the Energy page.
Common mistakes
- Assuming PS and hp are the same number.
- Comparing wheel horsepower with crankshaft horsepower without noting measurement method.
- Reading “brake horsepower” (bhp) as a different SI unit — it is still horsepower, measured under a particular test setup.
FAQs
- Which horsepower do car ads mean?
- US materials usually mean mechanical hp; many EU materials use PS/cv. Convert explicitly when crossing regions.
- Is boiler horsepower included?
- No — boiler horsepower is a separate historical unit for steam plant capacity and is not the same as mechanical hp.
Full guide: Power units: kW, hp, and PS
Related: Energy, Pressure, Travel & fuel.
Last updated: July 2026