Example:
15 horsepower (550 ft·lbf/s) = 1.11855e+19 fW
1 horsepower (550 ft·lbf/s) = 7.456999e+17 fW | 1 fW = 1.341022e-18 horsepower (550 ft·lbf/s)
Conversion Steps:
15 × (745.699871582 / 1e-15) = 1.11855e+19