Convert energy per unit mass
Energy per unit mass compares an energy quantity with the mass that stores or releases it. CalcOS converts supported values through joules per kilogram. Reciprocal units such as kilograms per joule reverse that relationship.
“Fuel Efficiency — Mass” does not mean vehicle mileage or thermodynamic efficiency. The quantity being converted is specific energy.
Named thermal-unit variants
| Unit | J/kg relationship | Status |
|---|---|---|
| 1 calₜₕ/g | 4,184 J/kg | exact |
| 1 calIT/g | 4,186.8 J/kg | exact |
| 1 BtuIT/lb | 1055.056 J ÷ 0.45359237 kg | NIST published factor |
| 1 kWh/kg | 3,600,000 J/kg | exact |
Higher and lower heating values are not interchangeable
A source may report a higher heating value, gross calorific value, lower heating value, or net calorific value. Those describe different test and water-vapor assumptions. This calculator preserves the number supplied and does not convert between those contexts.
No material assumptions
CalcOS does not assign typical values to gasoline, diesel, hydrogen, food, batteries, or any other material. It also does not estimate usable output after engine, drivetrain, electrical, or thermal losses.
Reciprocal zero and infinity
Zero energy per mass corresponds to infinite mass per energy. Zero mass per energy corresponds to infinite energy per mass. The calculator displays ∞ rather than hiding that mathematical limit.
Authoritative references: BIPM SI Brochure and NIST Special Publication 811.