Convert Kilowatts (kW) to Horsepower (HP)

One kilowatt is equal to approximately 1.34102 mechanical (imperial) horsepower. This is the most commonly used type of horsepower, also known as brake horsepower. There are other variants: one kilowatt equals approximately 1.35962 metric horsepower (PS). When comparing vehicle specifications, it is important to know which type of horsepower is being referenced, as the difference can amount to several HP in high-powered engines.

Mechanical (imperial) horsepower equals approximately 745.7 watts, while metric horsepower (PS, or Pferdestärke in German) equals approximately 735.5 watts. The mechanical horsepower was defined by James Watt based on the output of draft horses. Metric horsepower was later defined as the power needed to lift 75 kilograms by one meter per second. US and UK markets use mechanical HP, while European and Japanese markets often use PS (metric HP).

To convert a car engine's power from kW to HP, multiply the kilowatt value by 1.34102. For example, a car rated at 150 kW produces approximately 201 HP (150 × 1.34102 = 201.15 HP). Many European car manufacturers list engine power in kW on specification sheets, while US, UK, and Australian markets prefer HP. Electric vehicle manufacturers increasingly use kW, as it is the SI standard for power measurement.

Electric car motors are measured in kW because the kilowatt is the standard SI unit for power, and it relates directly to electrical measurements (power = voltage × current). Since electric motors draw power from batteries measured in kilowatt-hours (kWh), using kW for motor output provides a consistent measurement framework. However, manufacturers often also list the equivalent horsepower to help consumers compare with traditional combustion engines. For example, a Tesla Model 3 has motors producing about 283 kW (379 HP).

The term horsepower was coined by Scottish engineer James Watt in the late 18th century to market his improved steam engine. Watt needed a way to compare his engine's output to the work of draft horses that it would replace. Through experiments with mill horses, he estimated that a horse could perform 33,000 foot-pounds of work per minute, which he defined as one horsepower. While the actual output of a horse varies, Watt's definition became the standard and has persisted for over 200 years.