ISO 17507:2025 ยท Gas engine fuels
Calculate Methane Number
Methane number describes the resistance of a gaseous fuel to engine knock. This site brings together the two calculation methods from the ISO 17507 series, each with its own input requirements and range of applicability.
Choose a calculation method
Both calculators accept volume, mole, or mass compositions and convert them according to ISO 14912:2025 before applying the selected method.
MNc
ISO 17507-1:2025
The MNc method distributes combustible components among the standard's predefined ternary systems and combines the methane numbers calculated for those systems. The result includes spread and system shares for reviewing calculation consistency.
Method and validation
Input handling, ternary systems, and interpretation of spread.
Compare results from the MNc calculator with ISO reference examples.
PKI
ISO 17507-2:2025
The PKI method calculates the propane knock index from the gas composition, then converts that index to a methane number. The calculator reports both values.
Method and validation
Input handling, calculation of PKI, and method limits.
Compare results from the PKI calculator with ISO reference examples.
Using methane number results
Choose the method appropriate to your application and identify it when reporting a methane number. Check the supported components and method limits before interpreting a result. A calculated value does not guarantee the behaviour of a particular engine.
These are independent implementations, not official or certified reference software. The validation pages provide context for comparison with the examples in each standard. Read the disclaimer before relying on a result.