Fuel Energy Content Calculator
Calculate the energy content of gasoline, diesel, natural gas, or propane in BTU and kilojoules.
Compare fuel types by energy density.
Energy Content
Energy content measures how much usable energy a fuel contains per unit volume or mass.
Energy density by fuel type:
| Fuel | BTU per gallon | BTU per unit |
|---|---|---|
| Gasoline | 120,286 BTU/gal | 18,400 BTU/lb |
| Diesel | 137,381 BTU/gal | 18,500 BTU/lb |
| Natural Gas | — | 1,037 BTU/ft³ |
| Propane | 91,452 BTU/gal | 21,661 BTU/lb |
Unit conversions:
- 1 BTU = 1.055 kJ
- 1 therm = 100,000 BTU
- 1 gallon gasoline ≈ 33.7 kWh of electricity
- 1 gallon diesel ≈ 38.3 kWh
Practical comparisons:
- 1 gallon gasoline ≈ 1.13 gallons propane (by energy)
- 1 gallon diesel ≈ 1.14 gallons gasoline (by energy)
- 1 gallon gasoline ≈ 115.8 ft³ natural gas (by energy)
Efficiency note: Actual useful energy depends on conversion efficiency — internal combustion engines use only 20–40% of fuel energy.