Foot-pounds Per Second to Horsepower (ft⋅lbf/s to hp)
1 foot-pound per second equals 0.001818181818 horsepower (rounded).
How to convert foot-pounds per second to horsepower
To convert foot-pounds per second to horsepower, multiply the number of foot-pounds per second by 0.001818181818. The factor is rounded to 10 significant digits. To go the other way, multiply horsepower by 550.
horsepower = foot-pounds per second × 0.001818181818
Example: 10 foot-pounds per second = 0.01818181818 horsepower.
Several different horsepower units exist. This site lists mechanical (745.7 W), metric (735.5 W) and electrical (746 W) horsepower separately.
About these units
Foot-pound Per Second (ft⋅lbf/s)
About 1.3558 watts. A horsepower is 550 of these.
Engineers in the English-speaking world measured work as force times distance, so a pound-force lifted through a foot became a foot-pound, and doing it each second gave the foot-pound per second. It is the base from which horsepower is built, since the imperial horsepower is defined as 550 foot-pounds per second, or 33,000 per minute, the figure fixed by James Watt and Matthew Boulton in 1783.
In SI terms one foot-pound per second is about 1.3558 watts, and NIST lists 1.355818 watts without marking it exact. The reverse is 1 watt equal to 0.7375621 foot-pounds per second. Multiplying 550 by 1.3558 gives about 745.7 watts, the usual value for a mechanical horsepower. The unit is rarely quoted on its own today, though it appears in older mechanics texts and in small-scale power estimates.
1 foot-pound per second = 1.355817948 watts (approximately).
Sources: Wikipedia: Horsepower; Wikipedia: Watt; NIST SP 811, Appendix B.8
Horsepower (hp)
The mechanical horsepower: 550 foot-pounds per second, about 745.7 watts. James Watt coined it to compare steam engines with draft horses.
Horsepower was a sales pitch before it was a unit. Late in the 18th century the Scottish engineer James Watt adopted the term to compare the output of steam engines with the draft horses they replaced. His 1782 experiments found that a brewery horse could produce 32,400 foot-pounds-force per minute, and in 1783 he and Matthew Boulton standardized the figure at 33,000 foot-pounds-force per minute. Customers could then be told how many horses an engine would replace.
That figure works out to 550 foot-pounds-force per second, or about 745.7 watts: the power needed to lift 550 pounds by one foot in one second. Several cousins exist, including metric horsepower and electrical horsepower, defined as exactly 746 W. Car ratings added more confusion. Early British taxable horsepower was a formula based on bore and cylinder count, not measured output, and American ratings before 1972 used SAE gross brake horsepower, measured without accessories. In the European Union, horsepower may be used only as a supplementary unit under Directive 80/181/EEC, in force from 1 January 2010.
1 horsepower = 745.6998716 watts (approximately).
Sources: Wikipedia: Horsepower; Wikipedia: Metric horsepower
Related conversions
- Horsepower to foot-pounds per second (reverse)
- Foot-pounds per second to watts
- Foot-pounds per second to kilowatts
- Watts to horsepower
- Kilowatts to horsepower
- Megawatts to horsepower
- Gigawatts to horsepower
- Metric horsepower to horsepower
- BTU per hour to horsepower
- Milliwatts to horsepower
- Electrical horsepower to horsepower
- Tons of refrigeration to horsepower
- Kilocalories per hour to horsepower
- Calories per second to horsepower
- Ergs per second to horsepower
See all power units.