Heat of Combustion Calculator
Calculate the heat released when burning fuels.
Choose from methane, ethanol, propane, octane, hydrogen, or enter a custom combustion enthalpy.
The heat of combustion (ΔH_combustion) is the enthalpy change when one mole of a substance burns completely in excess oxygen under standard conditions (25°C, 1 atm).
Formula:
q = |ΔH_c| × n
where n = moles of fuel burned.
Standard heats of combustion (higher heating values, liquid water product):
| Fuel | Molar Mass (g/mol) | ΔH_c (kJ/mol) | Energy/g (kJ/g) |
|---|---|---|---|
| Hydrogen (H₂) | 2.016 | −285.8 | −141.8 |
| Methane (CH₄) | 16.04 | −890.4 | −55.5 |
| Ethanol (C₂H₅OH) | 46.07 | −1366.8 | −29.7 |
| Propane (C₃H₈) | 44.10 | −2220.0 | −50.3 |
| Butane (C₄H₁₀) | 58.12 | −2877.5 | −49.5 |
| Octane (C₈H₁₈) | 114.2 | −5471.0 | −47.9 |
| Carbon (graphite) | 12.01 | −393.5 | −32.8 |
| Glucose (C₆H₁₂O₆) | 180.2 | −2803.0 | −15.6 |
Higher vs Lower Heating Value:
- Higher (HHV): water product is liquid — more heat released
- Lower (LHV): water product is gas — accounts for vaporization energy
Real-world energy comparison:
- 1 kg methane ≈ 55.5 MJ (LNG fuel)
- 1 kg gasoline (octane equivalent) ≈ 47.9 MJ
- 1 kg wood (dry) ≈ 15-18 MJ
- 1 kg TNT (explosive equivalent) ≈ 4.6 MJ
- 1 kg hydrogen ≈ 141.8 MJ (highest energy density by mass of any fuel)
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
SuperGlobalCalculator is independently built and maintained. See how we build and verify our calculators.