Car Engine HP to Watts: How Powerful Is Your Car in kW?

Car Engine HP to Kilowatts (kW) Conversion

For over a century, the power of internal combustion engines has been universally advertised in Horsepower (HP). However, as the world transitions to Electric Vehicles (EVs) and global engineering standards converge, measuring vehicle power in Kilowatts (kW) is becoming the norm. In places like Europe and Australia, kW is already standard on vehicle registration documents.

Why Use Kilowatts?

The Kilowatt is a standard SI (International System of Units) metric. It is universal and applies identically to internal combustion engines, electric motors, and wind turbines. Horsepower, on the other hand, has multiple conflicting definitions (Mechanical vs Metric).

The Conversion Formulas

1. Converting Mechanical (Imperial) HP to kW

This is the standard used in the United States and the UK.

2. Converting Metric HP (PS, cv) to kW

This is the standard used for European and Asian combustion vehicles.

Worked Example: Converting a Sports Car's Power

Imagine a modern sports car is advertised in the US as having 450 HP (Mechanical).

Power in kW = 450 × 0.7457 = 335.5 kW.

If that same car were sold in Germany, it might be advertised in Metric HP (PS):

Power in PS = 335.5 kW × 1.3596 = 456 PS.

This explains why European spec sheets for the exact same car sometimes show slightly higher "horsepower" numbers than US spec sheets!

EV Power: From kW back to HP

Electric vehicles natively measure their battery discharge and motor output in kilowatts. If you want to know how an EV compares to a traditional gas car, you multiply its kW rating by 1.34.