HP and kW: formula and background
Everything about converting engine power ratings
The metric horsepower (PS) is a technical power unit that is still common in the automotive world today, even though official EU documents require kilowatts (kW). The conversion formula is: kW = HP × 0.735499. Conversely: HP = kW ÷ 0.735499. The number 0.735499 comes from the physical definition: one metric horsepower is the power needed to lift 75 kg by one metre in one second – equivalent to 75 × 9.80665 = 735.499 watts.
In the EU vehicle registration certificate (Zulassungsbescheinigung Teil I), the engine power is officially listed in kW in field P.2. To get the HP figure from it, divide the kW value by 0.735499. Example: 110 kW ÷ 0.735499 = 149.55 HP. Vehicle brochures usually round this to whole HP figures.
By comparison, the British/American horsepower (hp)is slightly different: 1 hp = 0.7457 kW, roughly 1% less than a metric horsepower. This can lead to small discrepancies for vehicles imported from the US or the UK. Our calculator uses the metric horsepower (PS, DIN 66036), which is the standard in Germany and Europe.
Need more than HP and kW – say watts, megawatts, or British horsepower (HP)? Use our power converter for all common power units.