Kilowatt (kW)

A kilowatt (kW) is 1,000 watts, the SI unit of power. In the EU a motorcycle's engine output is officially stated in kilowatts in the registration and type-approval documents, even if brochures also quote horsepower. One kilowatt equals about 1.36 metric horsepower (PS).

Kilowatts matter for licensing: an A2 licence allows motorcycles of up to 35 kW, with a power-to-weight ratio of no more than 0.2 kW per kg, and a bike restricted to A2 must not be derived from a model with more than double that power. Electric motorcycles are also rated in kW, often with separate continuous and peak figures.

For electrical systems, kilowatt-hours (kWh) measure stored energy, such as an electric bike's battery capacity.