Convert Foot-Pounds per Pound to Joules per Kilogram
Instantly convert Foot-Pounds per Pound (ft·lbf/lb) to Joules per Kilogram (J/kg) with our free online calculator.
Formula: ft·lbf/lb to J/kg — multiply by 2.98907
Reference Table
| Foot-Pounds per Pound (ft·lbf/lb) | Joules per Kilogram (J/kg) |
|---|---|
| 1 | 2.98907 |
| 5 | 14.9453 |
| 10 | 29.8907 |
| 25 | 74.7267 |
| 50 | 149.453 |
| 100 | 298.907 |
How to Convert Foot-Pounds per Pound to Joules per Kilogram
Formula
To convert Foot-Pounds per Pound (ft·lbf/lb) to Joules per Kilogram (J/kg): multiply by 2.98907
Step-by-Step
- Start with your value in Foot-Pounds per Pound (ft·lbf/lb).
- Multiply by 2.98907 to perform the conversion.
- The result is your value expressed in Joules per Kilogram (J/kg).
Conversion Factor
1 ft·lbf/lb = 2.98907 J/kg
Reverse Factor
1 J/kg = 0.334552 ft·lbf/lb
Worked Example
Convert 25 Foot-Pounds per Pound to Joules per Kilogram: 25 ft·lbf/lb = 74.7267 J/kg
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 Joule per Kilogram (J/kg)
The SI unit of specific energy (energy per unit mass) per ISO 80000-5 §5-15 — used for gravimetric energy density of fuels, batteries, explosives, and propellants. J/kg is the universal unit for cross-technology energy-storage comparisons, and the natural unit for kinetic-energy-per-mass (E_k/m = ½v² in J/kg = m²/s²). Reference values for energy-storage media per Sandia National Labs / DOE battery testing protocols and NFPA 921 fire-investigation reference data: lithium-ion 18650 cell ~550,000 J/kg (gravimetric); lithium-iron-phosphate (LFP, LiFePO₄) cells 360,000-450,000 J/kg; lead-acid battery 110,000-180,000 J/kg; gasoline 46,400,000 J/kg lower heating value (LHV) per ASTM D4868; diesel 45,500,000 J/kg LHV; coal (bituminous) ~24,000,000 J/kg; TNT 4,184,000 J/kg (the explosive-yield reference standard, basis of 'megaton' nuclear yield); hydrogen H₂ gas 120,000,000 J/kg LHV (highest gravimetric of any chemical fuel); jet fuel Jet-A 43,150,000 J/kg per ASTM D1655. Specific energy is also the key metric for compressed-air storage (CAES), pumped-hydro per-mass equivalent (gh = 9.81·h J/kg), and projectile kinetic energy per unit mass.
Quick Facts
- 1 Foot-Pound per Pound equals 2.98907 Joules per Kilogram
- 1 Joule per Kilogram equals 0.334552 Foot-Pounds per Pound
- Foot-Pound per Pound is a unit of specific energy
- Joule per Kilogram 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
- The Joule per Kilogram belongs to the metric system
Common Foot-Pound per Pound to Joule per Kilogram Conversions
| Foot-Pounds per Pound (ft·lbf/lb) | Joules per Kilogram (J/kg) |
|---|---|
| 0.01 | 0.0298907 |
| 0.1 | 0.298907 |
| 0.25 | 0.747267 |
| 0.5 | 1.49453 |
| 1 | 2.98907 |
| 2 | 5.97814 |
| 3 | 8.96721 |
| 5 | 14.9453 |
| 10 | 29.8907 |
| 15 | 44.8361 |
| 20 | 59.7814 |
| 25 | 74.7267 |
| 50 | 149.453 |
| 75 | 224.18 |
| 100 | 298.907 |
| 250 | 747.267 |
| 500 | 1494.53 |
| 1000 | 2989.07 |
| 5000 | 14945.4 |
| 10000 | 29890.7 |
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 Joules per Kilogram
The Joule per Kilogram (symbol: J/kg) is a unit of specific energy. The SI unit of specific energy (energy per unit mass) per ISO 80000-5 §5-15 — used for gravimetric energy density of fuels, batteries, explosives, and propellants. J/kg is the universal unit for cross-technology energy-storage comparisons, and the natural unit for kinetic-energy-per-mass (E_k/m = ½v² in J/kg = m²/s²). Reference values for energy-storage media per Sandia National Labs / DOE battery testing protocols and NFPA 921 fire-investigation reference data: lithium-ion 18650 cell ~550,000 J/kg (gravimetric); lithium-iron-phosphate (LFP, LiFePO₄) cells 360,000-450,000 J/kg; lead-acid battery 110,000-180,000 J/kg; gasoline 46,400,000 J/kg lower heating value (LHV) per ASTM D4868; diesel 45,500,000 J/kg LHV; coal (bituminous) ~24,000,000 J/kg; TNT 4,184,000 J/kg (the explosive-yield reference standard, basis of 'megaton' nuclear yield); hydrogen H₂ gas 120,000,000 J/kg LHV (highest gravimetric of any chemical fuel); jet fuel Jet-A 43,150,000 J/kg per ASTM D1655. Specific energy is also the key metric for compressed-air storage (CAES), pumped-hydro per-mass equivalent (gh = 9.81·h J/kg), and projectile kinetic energy per unit mass.
It belongs to the metric measurement system.
Joules per Kilogram are commonly used in fuel comparison, battery technology, and rocket propulsion.
Why Convert Foot-Pounds per Pound to Joules per Kilogram?
Converting between Foot-Pounds per Pound and Joules per Kilogram 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 Joules per Kilogram?
An imperial specific-energy unit equal to approximately 2. To convert Foot-Pounds per Pound to Joules per Kilogram, multiply by 2.98907. For example, 25 ft·lbf/lb equals 74.7267 J/kg.
How many Joules per Kilogram are in 1 Foot-Pound per Pound?
There are 2.98907 Joules per Kilogram in 1 Foot-Pound per Pound.
How many Foot-Pounds per Pound are in 1 Joule per Kilogram?
There are 0.334552 Foot-Pounds per Pound in 1 Joule per Kilogram.
What is the formula for Foot-Pound per Pound to Joule per Kilogram conversion?
The formula is: multiply by 2.98907. This means 1 ft·lbf/lb = 2.98907 J/kg.
Is a Foot-Pound per Pound bigger than a Joule per Kilogram?
No. One Foot-Pound per Pound is smaller than one Joule per Kilogram because 1 ft·lbf/lb equals 2.98907 J/kg, which is greater than 1.
When do you need to convert between Foot-Pounds per Pound and Joules per Kilogram?
The SI unit of specific energy (energy per unit mass) per ISO 80000-5 §5-15 — used for gravimetric energy density of fuels, batteries, explosives, and propellants. Foot-Pound per Pound and Joule per Kilogram 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.