This Technical Report describes methods for the calculation of the methane number (MN) of dry natural gas when the composition of the gas by mole fraction is known.

If the difference of MN between two calculation methods is more than 6, it is recommended to use a test method to determine MN for the gas.

The Gas Research Institute (GRI) methods are used to calculate methane number, MN, and motor octane number, MON, of gas; the linear relation is useful in determining and comparing the knock resistance of high methane content natural gas.