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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.

-OR-

• 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

### Notes

• 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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