Enter a motor or pump's horsepower rating to convert it to watts — useful for sizing a generator, inverter, or breaker for HP-rated equipment.
A motor's HP rating describes mechanical output, not electrical input — because no motor is 100% efficient, the actual electricity it draws is somewhat higher than the HP-to-watts conversion alone suggests.
Horsepower is a mechanical output measurement, common on pumps, generators, and motors, while watts measure electrical power — the two use a fixed conversion factor, but for an actual electric motor, the wattage it draws from an outlet or generator is higher than the raw HP conversion because motors lose some energy as heat. This matters directly for sizing a generator or breaker for HP-rated equipment like a well pump or air compressor — use the electrical input figure, not the raw output HP conversion, for that sizing.
Use the electrical input watts (after accounting for motor efficiency), not the raw HP-to-watts conversion — the generator needs to supply what the motor actually draws from the outlet, which is higher than its mechanical output alone.
Mechanical (or "imperial") horsepower and metric horsepower were defined independently and differ by about 1.4% — most U.S. equipment specs use mechanical HP (746W), so that's the safer default unless the equipment specifically states metric HP.