The Wobbe Index indicates the interchange ability of fuel gases and is the best indicator of the similarity between natural gas and a specific propane-air mixture.

The Wobbe Index indicates the interchange ability of fuel gases and is the best indicator of the similarity between natural gas and a specific propane-air mixture.

Fuel Gas	Upper Wobbe Index (kcal/Nm3)	Lower Wobbe Index (kcal/Nm3)
Hydrogen	11,528	9,714
Methane	12,735	11,452
Ethane	16,298	14,931
Ethylene	15,253	14,344
Natural Gas	12,837	11,597
Propane	19,376	17,814
Propylene	18,413	17,180
n-Butane	22,066	20,336
Iso-Butane	21,980	20,247
Butylene-1	21,142	19,728
LPG	20,755	19,106
Acetylene	14,655	14,141
Carbon Monoxide	3,060	3,060