Horsepower ↔ kW ↔ PS Converter
Convert between mechanical horsepower (hp), kilowatts (kW), and metric horsepower (PS / CV / ch). Match US, European, and SI power figures without mixing definitions.
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Result
The formula
All conversions route through the watt. Mechanical horsepower is defined as 745.699872 W; metric horsepower (PS) is 735.49875 W. Kilowatts are simply watts ÷ 1,000.
Worked example
- 250 hp → watts = 250 × 745.699872
- kW = 186,424.968 ÷ 1,000 = 186.425 kW
- PS = 186,424.968 ÷ 735.49875 ≈ 253.5 PS
Result: 250 hp ≈ 186.4 kW ≈ 253.5 PS
How automotive power units convert
“Horsepower” is ambiguous until you know which definition a brochure uses. This converter sticks to mechanical hp and DIN-style metric PS.
Mechanical horsepower
The mechanical (imperial) horsepower used in many US contexts is exactly 745.699872 W by conventional conversion to the SI watt.
Metric horsepower (PS)
PS (Pferdestärke), CV, and ch are the metric horsepower of 75 kgf·m/s = 735.49875 W. European type-approval figures are often in kW with PS shown alongside.
What we do not model
No SAE vs DIN correction curves, no wheel vs crank, no electrical motor peak vs continuous ratings — pure unit math.
Interesting facts
hp and PS are close
One mechanical hp is about 1.014 PS. Mixing them on a 300-unit engine only shifts the headline by a few “horsepower,” but it still matters for precise comparisons.
kW is the SI unit
Official EU documents emphasize kilowatts. Marketing still quotes PS because drivers recognize it.
Brake horsepower
bhp usually means power measured at the crank on a brake dyno — still in hp or kW, not a separate conversion factor.
Electric vehicle ratings
EV peak kW can exceed sustained output. Convert the number you are given; do not assume peak equals continuous highway power.
Frequently asked questions
1 mechanical hp ≈ 0.7457 kW. 1 PS ≈ 0.7355 kW.
hp ≈ kW ÷ 0.7457, or kW × 1.341. For PS, divide kW by 0.7355 (≈ kW × 1.360).
Yes in practice — PS, CV, and ch all refer to metric horsepower (≈ 735.5 W).
Rounding, different test standards (SAE, ECE, JIS), and whether the figure is crank or wheel power cause small gaps.
Those are different historical definitions. This tool is for automotive mechanical hp, PS, and kW only.
References
- NIST Special Publication 811 — Guide for the Use of SI Authoritative SI conversions including horsepower relationships.
- SI Brochure Defines the watt; horsepower units are non-SI.