Natural Gas Heating Value Calculator

Work out natural gas heating value instantly with clear inputs, formula shown and shareable results.

About Natural Gas Heating Value Calculator

Heating value is the mole-weighted sum of component heating values: methane 37.71 MJ/m3 gross, ethane 66.07 and propane 93.94, with nitrogen and carbon dioxide contributing nothing. The Wobbe index, heating value divided by the square root of relative density, governs burner interchangeability and is the specification that matters for appliances.

Formulas

Heating value

HHV = sum of mole fraction x component gross heating value

Wobbe index

Wobbe = HHV / sqrt(relative density)

Worked example

With the default values below, Natural Gas Heating Value Calculator returns Gross Heating Value of 38.7451. Change any input above and every figure here is recalculated in your browser.

Inputs used

Methaneaccepts 0–100 %: 92 %
Ethaneaccepts 0–100 %: 4 %
Propaneaccepts 0–100 %: 1.5 %
Nitrogen And Carbon Dioxideaccepts 0–100 %: 2.5 %

Results

Gross Heating Value: 38.7451
Net Heating Value: 34.9475
Heating Value In Btu Per scf: 1,039.9
Wobbe Index: 50.106

Step by step

1Values used
2Heating value
3Wobbe index
4Gross Heating Value= 38.7451
5Net Heating Value= 34.9475
6Heating Value In Btu Per scf= 1,039.9
7Wobbe Index= 50.106

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Gross or net heating value?

Gas is usually sold on gross (higher) heating value, which counts the latent heat of the water formed. Efficiency of appliances that do not condense the flue gas should be assessed on net.

Why does the Wobbe index matter more than heating value?

Burners are set for a heat input at a given pressure. Two gases with the same heating value but different density deliver different heat through the same orifice; the Wobbe index captures that combined effect.