Horsepower (hp) is a unit of measurement that expresses the rate at which work is done.

1 hp represents the amount of power it takes to perform 33,000 ft.-lbs. of work in 1 minute.

Imagine a horse pulling coal out of a mine. A horse exerting 1 horsepower can raise:

  • 330 lbs. of coal 100 ft. in 1 minute.


  • 33 lbs. of coal 1,000 ft. in 1 minute.
  • Etc.

How is it measured?

  • Engine specs will list peak horsepower at a specific rpm.
  • A dynamometer (dyno) measures torque and uses it to calculate horsepower.
  • The formula to calculate horsepower is:

(rpm x Torque) ÷ 5,252 = Horsepower

For example, if an engine makes 325 lb-ft at 3,880 rpm, it would be:

(3,880 x 325) ÷ 5,252 = 240 hp


  • The difference between Torque and horsepower is:
    • Torque explains how MUCH has been accomplished.
    • Horsepower explains how FAST it's done.
  • Australia and other countries that use the metric system measure horsepower in Watts or Kilowatts.
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