Calculate the total heat energy released during the combustion of a specific mass of fuel.
Combustion Parameters
g
kJ/g
Calculation Results
Enter fuel mass and its heat value to calculate energy released
Overview
Heat of combustion (ΔH_comb) is the energy released as heat when one mole or one unit of mass of a substance undergoes complete combustion with oxygen. This is a critical value in chemical engineering, aerospace, and food science. The combustion process converts chemical potential energy stored in C-H and C-C bonds into thermal energy, typically producing CO₂ and H₂O as the primary products.
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Pro Tips
The formula is Q = m × ΔH_comb, where Q is total heat, m is mass, and ΔH_comb is the specific heat value.
HHV (Higher Heating Value) is always greater than LHV (Lower Heating Value) because it includes the latent heat of vaporization of water.
Most industrial and automotive specifications use LHV since exhaust gases are usually too hot for water to condense.
When using the calculator, ensure your mass and heat value use the same base units (e.g., grams and kJ/g, or kg and MJ/kg).
Stoichiometry can tell you exactly how much oxygen you'll need for any given amount of fuel.
In nutrition, 'Calories' are actually Kilocalories (kcal). 1 kcal = 4.184 kJ.
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Fun Facts
"Hydrogen has the highest energy density by mass (141.8 MJ/kg), which is why it's the chosen fuel for space rocket stages."
"Diamonds can actually burn! Pure carbon (diamond) has a heat of combustion of ~395.4 kJ per mole."
"Fat in your body has a 'heat of combustion' of about 37 kJ/g (9 kcal/g), which is higher than carbs or protein (17 kJ/g)."
"The 'Lower Heating Value' (LHV) assumes water remains a gas; the 'Higher Heating Value' (HHV) assumes it condenses, releasing extra energy."
"TNT actually has a relatively low heat of combustion (4.6 MJ/kg) compared to gasoline; its power comes from the speed of the reaction, not total energy."
"Spontaneous combustion occurs when a substance with a low ignition point starts to burn due to internal heat buildup (like piles of oily rags)."
Formula: Q = m · ΔH_comb
Energy Densities for Common Fuels
Energy density comparison of common fuels
Hydrogen leads with 142 MJ/kg, followed by fossil fuels
