Example:
15 horsepower (550 ft·lbf/s) = 11185498.073735 mW
1 horsepower (550 ft·lbf/s) = 745699.871582 mW | 1 mW = 0.000001 horsepower (550 ft·lbf/s)
Conversion Steps:
15 × (745.699871582 / 0.001) = 11185498.073734501