BTU/hr to Horsepower
Convert BTU per hour to mechanical horsepower (hp) at the fixed ratio 1 hp = 2,544.434 BTU/hr.
Interactive
Scale explorer
Drag the slider or click a tier to see where your BTU/hr value lands on the equipment scale — with live hp output.
Fundamentals
What is BTU/hr to hp?
BTU/hr to Horsepower converts BTU per hour to mechanical horsepower (hp) by multiplying the BTU/hr value by 0.00039301. One mechanical horsepower equals 745.69987 watts, or 2,544.434 BTU/hr. The two formulas are P(hp) = P(BTU/hr) × 0.00039301 and P(hp) = P(BTU/hr) / 2,544.434. Horsepower still appears on motors, pumps, and older HVAC equipment, so the conversion bridges modern BTU/hr labels with legacy specs.
Mechanical horsepower (hp) is a unit of power defined as 550 foot-pounds per second, or 745.69987 watts. James Watt popularized it to compare steam engines to draft horses, which could reportedly sustain about that output.
Two other horsepower definitions exist: metric hp (735.49875 W) and electrical hp (746 W). This page uses mechanical hp, the standard in U.S. HVAC and motor specs.
Boiler horsepower is a separate unit entirely — 33,475 BTU/hr per bhp — and does not equal mechanical hp. Always confirm which horsepower a spec refers to.
Formula
BTU/hr to hp formula
Convert 12,000 BTU/hr — the one-ton AC benchmark — to horsepower. The result, 4.716 hp, represents the thermal power of the unit.
How to convert BTU/hr to hp
Three steps complete the conversion:
Take the BTU/hr value
Read it from the equipment nameplate or spec sheet.
Divide by 2,544.434
Or multiply by 0.00039301. Both return the same mechanical horsepower value.
Compare to motor specs
Match the result against motor hp ratings for cross-system sizing.
Applications
When to convert BTU/hr to hp
Real-world scenarios where this conversion shows up in engineering, HVAC, and equipment specification work.
Match HVAC compressor BTU/hr specs to motor hp ratings.
Calculate the thermal equivalent of pump motor rejection heat.
Convert legacy BTU/hr specs from the steam era to modern hp values.
Size radiators and heat exchangers when specs use both units.
Solve thermodynamics problems where the same power appears in both systems.
Guidance
Tips and common pitfalls
Mechanical hp = 745.7 W. Metric hp = 735.5 W. Electrical hp = 746 W. Boiler hp = 9,810 W. Confirm before converting.
A '5 hp motor' draws enough electricity to deliver 5 hp of shaft power. Heat output includes losses on top of that.
For precise work, convert BTU/hr → W, then W → hp. Combined factors introduce rounding unless you keep enough digits.
Reference
BTU/hr to hp conversion table
| BTU per hour (BTU/hr) | Mechanical horsepower (hp) |
|---|---|
| 1,000 BTU/hr | 0.393015 hp |
| 2,544 BTU/hr | 0.99983 hp |
| 5,000 BTU/hr | 1.9651 hp |
| 10,000 BTU/hr | 3.9301 hp |
| 12,000 BTU/hr | 4.7162 hp |
| 18,000 BTU/hr | 7.0743 hp |
| 24,000 BTU/hr | 9.4324 hp |
| 36,000 BTU/hr | 14.1485 hp |
| 50,000 BTU/hr | 19.6507 hp |
| 60,000 BTU/hr | 23.5809 hp |
| 100,000 BTU/hr | 39.3015 hp |
Watt chose 550 foot-pounds per second after measuring strong draft horses pulling loads at a brewery. Real horses can briefly exceed 15 hp in short bursts.
Questions
Frequently asked
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