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Horsepower

 

Horsepower Formula

\( HP \;=\; \dfrac{ F \cdot d }{ t }\)     (Horsepower)

\( F \;=\; \dfrac{ HP \cdot t }{ d }\)

\( d \;=\; \dfrac{  HP \cdot t }{ F }\)

\( t \;=\; \dfrac{  F \cdot d }{ HP }\)
Symbol English Metric
\( HP \) = horsepower \(lbf-ft\;/\;sec\) \(J\;/\;s\)
\( F \) = force \(lbf\) \(kg-m^2\;/\;s^2\) 
\( d \) = distance \(ft\) \(m\)
\( t \) = time \(sec\) \(s\)

horsepower 1Horsepower, 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.  In the context of engines, horsepower is used to measure the power output of an engine.  It is calculated by measuring the torque (rotational force) produced by the engine and multiplying it by the engine's rotational speed.

Horsepower is commonly used to compare the performance of different engines and vehicles.  A higher horsepower rating generally indicates a more powerful engine, which can result in better acceleration, higher top speed, and greater towing or hauling capacity.  However, horsepower alone does not tell the whole story of an engine's performance, as factors such as torque, fuel efficiency, and emissions must also be considered.

Horsepower Conversion Table
Multiply By To 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

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Horsepower Conversion Factor

  • 1 horsepower = 5252 RPM  -  When charting torque and horsepower, the math always cross at 5252 RPM. 
Mechanical Horsepower (Imperial Horsepower)
  • 1 HP  =  745.699872 or 746 watts (W)
  • 1 HP  =  0.7457 or 0.746 kilowatts (kW)
  • 1 HP  =  550 foot-pounds per second (ft-lbf/s)
  • 1 HP  =  33,000 foot-pounds per minute (ft-lbf/min)
  • 1 HP  ≈  1.014 metric horsepower (PS or CV)

Metric Horsepower (PS or CV)

  • 1 PS (Pferdestärke)  =  735.49875 or 735.5 watts (W)
  • 1 PS  =  0.7355 kilowatts (kW)
  • 1 PS  ≈  0.9863 mechanical horsepower (HP)

Electrical Horsepower

  • 1 HP (electric)  =  746 watts (W)
  • 1 HP (electric)  =  0.746 kilowatts (kW)

Boiler Horsepower

  • 1 Boiler HP  =  9,809.5 watts (W)
  • 1 Boiler HP  =  9.809 kilowatts (kW)
  • 1 Boiler HP  =  33,475 BTU/hour

Water Horsepower

  • 1 HP  =  3960 gal/min/foot
  • 1.341 HP  =  1 kW
  • 1 cu-ft / sec  =  448 GPM
  • 1 PSI  =  a head of 2.309 ft (water weight)

Other Units of Power Conversion

  • 1 HP = 42.44 BTU per minute (British Thermal Units)
  • 1 HP  ≈  2544.434187 or 2545 BTU per hour

Quick Conversion Factors

  • 1 kilowatt (kW)  =  1.341 HP (mechanical)
  • 1 watt (W)  ≈  0.001341 HP (mechanical)
  • 1 metric HP (PS)  =  0.986 mechanical HP