Convert Inch-Pound-Force to Horsepower-Hours
Convert Inch-Pound-Force (in·lbf) to Horsepower-Hours (hp·h) instantly and accurately.
Conversion Formula
hp·h = in·lbf × 4.208754209e-8
About Inch-Pound-Force
An inch-pound-force (in·lbf) is the work done by one pound-force through one inch - exactly 0.11298482902761670 J (= 1/12 ft·lbf). It is the dominant torque unit for small fasteners and precision instruments in the US: a #6-32 screw in aluminium is torqued to 4-6 in·lbf; a dental implant abutment screw to ~25-30 Ncm (2.2-2.7 in·lbf). Hobby servo motor torque is quoted in oz·in (1 in·lbf = 16 oz·in). Bicycle stem bolts are typically 4-6 Nm (35-53 in·lbf). 1 in·lbf = 0.11298 J = 1/12 ft·lbf = 11.298 Ncm.
About Horsepower-Hours
A horsepower-hour (hp·h) is the energy from one mechanical horsepower (745.6999 W) for one hour - exactly 2,684,519.54 J ≈ 2.685 MJ. James Watt coined the horsepower to compare his steam engines with mine horses; billing in hp·h preceded the kilowatt-hour tariff. The metric horsepower (PS = 75 kgf·m/s = 735.499 W) gives a slightly smaller metric-hp·h = 2,647,795 J, used in European and Japanese engine datasheets. Today the hp·h appears in marine engineering logs, mining energy accounting, and vintage industrial equipment. 1 hp·h = 2.6845 MJ = 0.74570 kWh = 641.19 kcal.
Quick Reference Table
| Inch-Pound-Force (in·lbf) | Horsepower-Hours (hp·h) |
|---|---|
| 1 in·lbf | 4.209 × 10-8 hp·h |
| 2 in·lbf | 8.418 × 10-8 hp·h |
| 5 in·lbf | 2.104 × 10-7 hp·h |
| 10 in·lbf | 4.209 × 10-7 hp·h |
| 25 in·lbf | 1.052 × 10-6 hp·h |
| 50 in·lbf | 2.104 × 10-6 hp·h |
| 100 in·lbf | 4.209 × 10-6 hp·h |