UnitConFuel Efficiency (Mass)
Fuel efficiency by mass, also called specific energy, measures how much energy a fuel contains for each unit of mass. The SI unit is joules per kilogram, though MJ/kg and BTU/lb are more practical in many fields. This converter is useful in combustion engineering, aerospace, and fuel comparison studies. It helps separate energy content from fuel economy and tank size.
Common conversions
| From | To |
|---|---|
| 1 Megajoule per Kilogram | 429.9226 BTU per Pound |
| 1 BTU per Pound | 2.326 Kilojoule per Kilogram |
| 42 Megajoule per Kilogram | 18,056.75 BTU per Pound |
| 44 Megajoule per Kilogram | 18,916.6 BTU per Pound |
| 1 Kilocalorie per Kilogram | 4.184 Kilojoule per Kilogram |
| 10000 BTU per Pound | 23.26 Megajoule per Kilogram |
Frequently asked questions
Specific energy is energy per unit mass. It helps compare fuels on a weight basis rather than a volume basis.
Mass-based values compare energy per kilogram or pound, while volume-based values compare energy per liter or gallon. The ranking of fuels can change depending on which basis you use.
Hydrogen is extremely high by mass, though it is much less favorable by volume. That is why mass and volume comparisons should not be mixed.