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Convert Foot-Pounds per Pound to BTU per Pound

Instantly convert Foot-Pounds per Pound (ft·lbf/lb) to BTU per Pound (BTU/lb) with our free online calculator.

Reviewed by Christopher FloiedUpdated

Formula: ft·lbf/lb to BTU/lbmultiply by 0.00128507

Reference Table

Foot-Pounds per Pound (ft·lbf/lb)BTU per Pound (BTU/lb)
10.00128507
50.00642534
100.0128507
250.0321267
500.0642534
1000.128507

How to Convert Foot-Pounds per Pound to BTU per Pound

Formula

To convert Foot-Pounds per Pound (ft·lbf/lb) to BTU per Pound (BTU/lb): multiply by 0.00128507

Step-by-Step

  1. Start with your value in Foot-Pounds per Pound (ft·lbf/lb).
  2. Multiply by 0.00128507 to perform the conversion.
  3. The result is your value expressed in BTU per Pound (BTU/lb).

Conversion Factor

1 ft·lbf/lb = 0.00128507 BTU/lb

Reverse Factor

1 BTU/lb = 778.168 ft·lbf/lb

Worked Example

Convert 25 Foot-Pounds per Pound to BTU per Pound: 25 ft·lbf/lb = 0.0321267 BTU/lb

About Foot-Pound per Pound (ft·lbf/lb)

An imperial specific-energy unit equal to approximately 2.98907 J/kg (1 ft·lbf = 1.35582 J; 1 lb = 0.45359237 kg; ratio = 2.98907). ft·lbf/lb is a niche US-engineering unit used primarily in: ballistic kinetic-energy-per-mass calculations (E_k/m for projectiles, where US ballistics literature historically uses imperial mass for the projectile and ft·lbf for muzzle energy — a .308 Winchester 168gr bullet at 2,650 fps muzzle velocity has specific energy ~109,000 ft·lbf/lb), US-edition mechanical-engineering textbooks for mechanical strain-energy-per-mass calculations (Shigley, Norton, Hibbeler in dual-unit editions), and head-loss / hydraulic-energy specific calculations in US civil-engineering hydraulics where the natural unit is feet-of-head (1 ft of head of water ≈ 1 ft·lbf/lb specific gravitational potential). For typical engineering specific-energy scales (gasoline, batteries, structural-strain energy), the ft·lbf/lb numerical value is large and unwieldy — gasoline LHV is ~15.5 million ft·lbf/lb — so US engineers usually convert to BTU/lb for fuel work and reserve ft·lbf/lb for kinetic and elastic-strain applications. Convert ft·lbf/lb to J/kg by multiplying by 2.98907.

About BTU per Pound (BTU/lb)

An imperial specific-energy unit equal to exactly 2,326 J/kg (1 BTU/lb = 1,055.06 J / 0.45359237 kg = 2,326.000 J/kg). BTU/lb is dominant on US steam tables, HVAC enthalpy/psychrometric calculations per ASHRAE Handbook Fundamentals chapter 1, heating-fuel and refining specific-energy reporting per API MPMS and GPSA Engineering Data Book, and natural-gas heating-value certification. Reference values: natural gas heating value (residential pipeline grade) ~22,000 BTU/lb HHV (higher heating value with water-vapor condensation credit); LNG 21,500 BTU/lb; #2 fuel oil ~19,500 BTU/lb; gasoline 19,500-20,000 BTU/lb LHV; coal anthracite 13,000-15,000 BTU/lb; bituminous 10,500-14,000 BTU/lb per ASTM D388 classification; sub-bituminous 8,500-13,000 BTU/lb; lignite 4,000-8,300 BTU/lb. Saturated liquid water at 70°F: h_f ≈ 38.1 BTU/lb; saturated steam at 14.7 psia: h_g ≈ 1,150.5 BTU/lb. Refrigerant enthalpy/entropy tables in US-edition ASHRAE Handbook and US-customary printings of Mollier h-s diagrams use BTU/lb throughout. Convert BTU/lb to kJ/kg by multiplying by 2.326.

Quick Facts

  • 1 Foot-Pound per Pound equals 0.00128507 BTU per Pound
  • 1 BTU per Pound equals 778.168 Foot-Pounds per Pound
  • Foot-Pound per Pound is a unit of specific energy
  • BTU per Pound is a unit of specific energy
  • This conversion is commonly used in fuel comparison, battery technology, and rocket propulsion
  • The Foot-Pound per Pound belongs to the imperial system

Common Foot-Pound per Pound to BTU per Pound Conversions

Foot-Pounds per Pound (ft·lbf/lb)BTU per Pound (BTU/lb)
0.010.0000128507
0.10.000128507
0.250.000321267
0.50.000642534
10.00128507
20.00257014
30.00385521
50.00642534
100.0128507
150.019276
200.0257014
250.0321267
500.0642534
750.0963802
1000.128507
2500.321267
5000.642534
10001.28507
50006.42534
1000012.8507

Understanding Foot-Pounds per Pound

The Foot-Pound per Pound (symbol: ft·lbf/lb) is a unit of specific energy. An imperial specific-energy unit equal to approximately 2.98907 J/kg (1 ft·lbf = 1.35582 J; 1 lb = 0.45359237 kg; ratio = 2.98907). ft·lbf/lb is a niche US-engineering unit used primarily in: ballistic kinetic-energy-per-mass calculations (E_k/m for projectiles, where US ballistics literature historically uses imperial mass for the projectile and ft·lbf for muzzle energy — a .308 Winchester 168gr bullet at 2,650 fps muzzle velocity has specific energy ~109,000 ft·lbf/lb), US-edition mechanical-engineering textbooks for mechanical strain-energy-per-mass calculations (Shigley, Norton, Hibbeler in dual-unit editions), and head-loss / hydraulic-energy specific calculations in US civil-engineering hydraulics where the natural unit is feet-of-head (1 ft of head of water ≈ 1 ft·lbf/lb specific gravitational potential). For typical engineering specific-energy scales (gasoline, batteries, structural-strain energy), the ft·lbf/lb numerical value is large and unwieldy — gasoline LHV is ~15.5 million ft·lbf/lb — so US engineers usually convert to BTU/lb for fuel work and reserve ft·lbf/lb for kinetic and elastic-strain applications. Convert ft·lbf/lb to J/kg by multiplying by 2.98907.

It belongs to the imperial measurement system.

Foot-Pounds per Pound are commonly used in fuel comparison, battery technology, and rocket propulsion.

Understanding BTU per Pound

The BTU per Pound (symbol: BTU/lb) is a unit of specific energy. An imperial specific-energy unit equal to exactly 2,326 J/kg (1 BTU/lb = 1,055.06 J / 0.45359237 kg = 2,326.000 J/kg). BTU/lb is dominant on US steam tables, HVAC enthalpy/psychrometric calculations per ASHRAE Handbook Fundamentals chapter 1, heating-fuel and refining specific-energy reporting per API MPMS and GPSA Engineering Data Book, and natural-gas heating-value certification. Reference values: natural gas heating value (residential pipeline grade) ~22,000 BTU/lb HHV (higher heating value with water-vapor condensation credit); LNG 21,500 BTU/lb; #2 fuel oil ~19,500 BTU/lb; gasoline 19,500-20,000 BTU/lb LHV; coal anthracite 13,000-15,000 BTU/lb; bituminous 10,500-14,000 BTU/lb per ASTM D388 classification; sub-bituminous 8,500-13,000 BTU/lb; lignite 4,000-8,300 BTU/lb. Saturated liquid water at 70°F: h_f ≈ 38.1 BTU/lb; saturated steam at 14.7 psia: h_g ≈ 1,150.5 BTU/lb. Refrigerant enthalpy/entropy tables in US-edition ASHRAE Handbook and US-customary printings of Mollier h-s diagrams use BTU/lb throughout. Convert BTU/lb to kJ/kg by multiplying by 2.326.

It belongs to the imperial measurement system.

BTU per Pound are commonly used in fuel comparison, battery technology, and rocket propulsion.

Why Convert Foot-Pounds per Pound to BTU per Pound?

Converting between Foot-Pounds per Pound and BTU per Pound is a frequent requirement for engineers, scientists, and students working with specific energy values. Different industries and regions favour different unit systems, so having a dependable conversion tool saves time and prevents errors in technical calculations. Whether you are verifying a specification sheet, cross-checking simulation results, or preparing a report for an international audience, accurate specific energy conversion is essential.

Frequently Asked Questions

How do I convert Foot-Pounds per Pound to BTU per Pound?

An imperial specific-energy unit equal to approximately 2. To convert Foot-Pounds per Pound to BTU per Pound, multiply by 0.00128507. For example, 25 ft·lbf/lb equals 0.0321267 BTU/lb.

How many BTU per Pound are in 1 Foot-Pound per Pound?

There are 0.00128507 BTU per Pound in 1 Foot-Pound per Pound.

How many Foot-Pounds per Pound are in 1 BTU per Pound?

There are 778.168 Foot-Pounds per Pound in 1 BTU per Pound.

What is the formula for Foot-Pound per Pound to BTU per Pound conversion?

The formula is: multiply by 0.00128507. This means 1 ft·lbf/lb = 0.00128507 BTU/lb.

Is a Foot-Pound per Pound bigger than a BTU per Pound?

Yes. One Foot-Pound per Pound is larger than one BTU per Pound because 1 ft·lbf/lb equals 0.00128507 BTU/lb, which is less than 1.

When do you need to convert between Foot-Pounds per Pound and BTU per Pound?

An imperial specific-energy unit equal to exactly 2,326 J/kg (1 BTU/lb = 1,055. Foot-Pound per Pound and BTU per Pound are both specific energy units, so conversion comes up whenever one source of information uses one unit and another uses the other — a classic cross-reference challenge in engineering, trade, travel, and everyday life.

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