What is the heating value of natural gas?

The heating value of natural gas is the amount of energy released when the gas is burned completely. Gross heating value (HHV) includes the latent heat of water vapor condensation, while net heating value (LHV) excludes it. Typical pipeline-quality natural gas has an HHV of 950-1150 Btu/scf depending on composition.

What is the Wobbe Index and why does it matter?

The Wobbe Index equals the gross heating value divided by the square root of the specific gravity (WI = HHV / sqrt(SG)). It is the key indicator of gas interchangeability for burner applications. Gases with similar Wobbe Indices produce similar heat release rates when burned at the same supply pressure, regardless of their individual compositions.

How is heating value calculated from gas composition?

Heating value is calculated as the mole-fraction-weighted sum of individual component heating values: HHV_mix = sum(yi x HHVi). Component heating values are published in GPA 2145 (Table of Physical Constants of Paraffin Hydrocarbons and Other Components of Natural Gas) at standard conditions of 60 deg F and 14.696 psia.

What is the difference between HHV and LHV?

HHV (Higher Heating Value) assumes all water produced by combustion condenses to liquid, recovering latent heat. LHV (Lower Heating Value) assumes water remains as vapor. For methane, HHV is 1010.0 Btu/scf vs LHV of 909.4 Btu/scf, a difference of about 10%. US gas industry uses HHV for custody transfer; European practice often uses LHV.

Heating Value from Gas Composition Calculator

Hydrocarbon Composition (mol%)

Methane (C1)

mol%

Ethane (C2)

mol%

Propane (C3)

mol%

i-Butane (iC4)

mol%

n-Butane (nC4)

mol%

i-Pentane (iC5)

mol%

n-Pentane (nC5)

mol%

Hexanes+ (C6+)

mol%

Non-Hydrocarbon Components (mol%)

Nitrogen (N2)

mol%

Carbon Dioxide (CO2)

mol%

Hydrogen Sulfide (H2S)

mol%

Helium (He)

mol%

Hydrogen (H2)

mol%

Oxygen (O2)

mol%

Water (H2O)

mol%

Total: 99.00 mol%

Options

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When enabled, composition is proportionally adjusted to sum to exactly 100 mol%.

Reference Conditions

Understanding Heating Value

HHV vs LHV
Gross Heating Value (HHV) includes latent heat from water vapor condensation. Net Heating Value (LHV) assumes water remains as vapor. Difference is approximately 10% for methane-rich gas.

Wobbe Index
WI = HHV / sqrt(SG). Key interchangeability parameter for burner applications. Gases with similar Wobbe Indices produce similar heat release at the same supply pressure.

Gas Quality Specifications
Pipeline-quality gas: HHV 950-1150 Btu/scf, total inerts (N2 + CO2) < 4%, H2S < 4 ppm (0.25 grain/100 scf). GPA 2145 provides the physical constants used for all heating value calculations.

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Results

Gross Heating Value (HHV)

Btu/scf

Net Heating Value (LHV) -

HHV (mass basis) -

Molecular Weight -

Specific Gravity (ideal) -

Specific Gravity (real) -

Wobbe Index -

BTU Factor -

GPM (C2+) -

GPM (C3+) -

Total Inerts (N2 + CO2) -

Formula

HHV = Σ(y_i × HHV_i)

HHV = Gross heating value (Btu/scf)

y_i = Mole fraction of component i

HHV_i = Heating value of component i (GPA 2145)

WI = HHV / √SG (Wobbe Index)

SG = MW_mix / 28.9625

Standards & References

GPA 2145
Table of Physical Constants of Paraffin Hydrocarbons and Other Components of Natural Gas
GPA 2172
Calculation of Gross Heating Value, Relative Density, Compressibility, and Theoretical Hydrocarbon Liquid Content
ISO 6976
Natural Gas — Calculation of Calorific Values, Density, and Wobbe Index
GPSA Engineering Data Book
Section 2: Product Specifications & Section 23: Physical Properties

Engineering Notes

HHV vs LHV: US gas industry uses HHV (higher heating value) for custody transfer and billing. LHV is ~10% lower for methane.
Pipeline spec: Typical HHV range is 950-1150 Btu/scf with total inerts < 4%
Wobbe Index: Target 1310-1390 Btu/scf for US residential appliances
H2S limit: Pipeline tariffs typically limit H2S to 4 ppm (0.25 grain/100 scf)
C6+ lumped: Hexanes+ properties use n-hexane as representative compound
Dry basis: Results assume dry gas at stated reference conditions

Quick Reference — Typical Gas Quality

Pure methane: HHV = 1010 Btu/scf, SG = 0.554
Lean pipeline gas: HHV = 1020-1040 Btu/scf
Rich gas: HHV = 1100-1200 Btu/scf
Landfill gas (50% CH4): HHV ~ 500 Btu/scf
LNG regasification: HHV = 1050-1100 Btu/scf

Heating Value from Gas Composition

Hydrocarbon Composition (mol%)

Non-Hydrocarbon Components (mol%)

Options

Understanding Heating Value

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Results

Formula

Standards & References

Engineering Notes

Quick Reference — Typical Gas Quality

Related Calculators

Gas Density

Z-Factor

Gas Conversions

Mcf to MMBtu