Convert Mechanical Horsepower to BTU per Hour (hp → BTU/h)

Converting mechanical horsepower to BTU per hour is straightforward: multiply by the conversion factor. Follow these three steps to do it by hand or in your head.

1. 1
   Take your value in mechanical horsepower

   Start with the number of mechanical horsepower (hp) you want to convert.
2. 2
   Multiply by 2,544.4336

   The conversion factor from hp to BTU/h is 2,544.4336. Multiply your value by this number.
3. 3
   Read the result in BTU per hour

   The result is your value in BTU per hour (BTU/h).

Multiply the value in mechanical horsepower by 2,544.4336. For the reverse direction, multiply by 0.000393.

• ✓1 hp = 745.7 W = 0.7457 kW.
• ✓US car ads quote hp; European ads quote kW or PS.
• ✓Metric horsepower (PS) differs by ~1.4% — be aware.

• ✗Assuming hp and PS are identical — 1.4% difference.
• ✗Using horsepower for electrical devices — watts more appropriate.
• ✗Confusing horsepower at engine flywheel vs wheel (transmission losses).

What is the Mechanical Horsepower?

Horsepower (hp) equals exactly 745.6998715822702 watts (mechanical horsepower) and is the American and British unit for car engines, motorcycles, motorboats, and traditional mechanical power ratings. James Watt invented the unit in the 1780s to market his steam engines: he calculated that a brewery horse could continuously turn a mill wheel at 33,000 ft·lb per minute, which became 1 horsepower. American cars typically range from 150 hp (economy) to 700 hp (sports cars), pickup trucks 250–500 hp, and large diesel trucks 400–600 hp. Outside the US, the metric horsepower (PS or CV, equal to 735.5 W — about 1.4% smaller than mechanical hp) is sometimes used. Horsepower relates to the watt (1 hp ≈ 745.7 W), the kilowatt (1 hp ≈ 0.746 kW), and the metric horsepower (1 hp ≈ 1.014 PS). Despite SI's preference for the watt, horsepower remains entrenched in automotive marketing.

• US car and motorcycle engine ratings
• Lawn mower and small engine specs
• US pump and compressor ratings

What is the BTU per Hour?

BTU per hour (BTU/h or BTUh) is the standard rating for American heating, air-conditioning, and refrigeration system capacity. A window air conditioner is typically 5,000–12,000 BTU/h, central residential AC ranges 24,000–60,000 BTU/h, and commercial chillers reach 100,000–1,000,000+ BTU/h. The unit's persistence in HVAC reflects American engineering tradition: it directly links cooling/heating capacity to the BTU energy unit familiar in gas-fired equipment. 12,000 BTU/h equals 'one ton of refrigeration' (a unit derived from the heat needed to melt 1 ton of ice in 24 hours), so AC sizes are sometimes given in 'tons' (a 3-ton AC = 36,000 BTU/h). BTU/h relates to the watt (1 W ≈ 3.412 BTU/h), the kilowatt (1 kW ≈ 3,412 BTU/h), and the ton of refrigeration (12,000 BTU/h = 1 ton). Outside the US, kW is dominant for HVAC capacity.

• US air conditioners and heat pumps
• US furnace and boiler ratings
• Some industrial heat-exchanger specs