kW to PS: The Formula and Physics Behind Engine Power

When you look at a car’s registration paper in Germany, France, or anywhere in the European Union, the official power figure is invariably listed in Kilowatts (kW). Yet in car dealerships, brochures, and casual conversation among motoring enthusiasts, Pferdestärke (PS) remains the dominant benchmark.

Why does this duality exist, and how do we convert between them accurately?

The Conversion Formula

To convert Kilowatts to Metric Horsepower:

PS = kW × 1.3596216

To convert Metric Horsepower back to Kilowatts:

kW = PS × 0.73549875

Where Does 1.35962 Come From?

By definition in metric physics:

• 1 PS (Pferdestärke) is defined as the work required to lift a mass of 75 kilograms against Earth’s gravitational acceleration (9.80665 m/s²) at a speed of 1 meter per second.
• Multiplying 75 × 9.80665 yields approximately 735.49875 Watts (or 0.73549875 kW).
• Taking the reciprocal: 1 / 0.73549875 = 1.3596216173.

Practical Automotive Examples

Vehicle Class	Power in kW	Power in PS	Mechanical HP
City Hatchback	55 kW	75 PS	74 hp
Compact Sedan	110 kW	150 PS	148 hp
Sports Coupe	221 kW	300 PS	296 hp
Performance Supercar	441 kW	600 PS	592 hp

Our online calculator makes this conversion instantaneous and mathematically rigorous.