Horsepower to Watts

Horsepower is an older unit for measuring power, while the watt is the standard SI unit used in science and engineering. This conversion works because 1 mechanical horsepower is defined as about 745.7 watts, so multiplying horsepower by 745.7 changes the unit without changing the actual power. It is useful whenever you need to compare engine power or mechanical output with electrical power in watts.

Use this formula when converting the power of engines, motors, pumps, or tools from horsepower into watts. It is especially helpful in physics, engineering, and product specifications where watts are the required unit.

• Using 745.7 for kilowatts instead of watts
• Multiplying watts by horsepower instead of converting horsepower into watts
• Mixing mechanical horsepower with metric horsepower without checking which definition is being used