# Horsepower

Written by Jerry Ratzlaff on . Posted in Fluid Dynamics

Horsepower, abbreviated as HP, is a measure of power or the rate of doing work. It is typically used to describe the work of an engine or machine and is the equivalent of moving 33,000 pounds through the distance of one foot in one minute.

## Horsepower formulas

 $$\large{ HP = \frac{ \tau \; s }{ 5252 } }$$ $$\large{ HP = W \; \left( \frac{ v }{ 234 } \right)^3 }$$ (estimated HP after quarter mile trap speed method) $$\large{ HP = \frac{W}{ \left( \frac{ ET }{ 5.825 } \right)^3 } }$$ (estimated HP after quarter mile ET (elapsed time) method)

### Where:

$$\large{ HP }$$ = horsepower

$$\large{ s }$$ = speed (rpm)

$$\large{ \tau }$$  (Greek symbol tau) = torque

$$\large{ v }$$ = velocity

$$\large{ W }$$ = weight

### Solve for:

$$\large{ s = \frac{ 5252\; HP }{ \tau } }$$

$$\large{ \tau = \frac{ 5252\; HP }{ s } }$$

## horsepower conversion table

Horsepower Conversion Table
MultiplyByTo get
2545.45766 BTU per hour, BTU/hr
42.42429433 BTU per minute, BTU/min
0.707071572 BTU per second, BTU/sec
1980796.979 foot pound-force per hour
33013.28298 foot pound-force per minute
550.221383 foot pound-force per second
1 horsepower, hp
17702.8489 pound square foot per cubic second
0.212121472 ton of refrigeration, ton
2.6856E+13 dyne centimeter per hour
4.476E+11 dyne centimeter per minute
7460000000 dyne centimeter per second
2685600 joule per hour
44760 joule per minute
746 joule per second
746 watt, W
0.746 kilowatt, kW
0.000746 megawatt, MW
0.000000746 gigawatt, GW
2685600 newton meter per hour
44760 newton meter per minute
746 newton meter per second