The formula
kW = hp × 0.7355 (metric) | kW = hp × 0.7457 (mechanical)
- hp
- horsepower — check which definition the nameplate uses
- kW
- kilowatts of shaft output, not of supply input
Worked example
A 5 hp motor, metric horsepower as marked in India.
- kW = 5 × 0.7355
- kW = 3.677
- Using mechanical hp instead: 5 × 0.7457 = 3.729 kW
3.677 kW — or 3.729 kW if the nameplate means mechanical horsepower.
Where you'll use it
Reading a motor nameplate, comparing pumps and compressors quoted in different units, and translating an hp rating into the kW figure every other calculation needs. Remember the result is output power: the supply provides that divided by the efficiency.