The term Critical Path Method (CPM) refers to a specific technique of schedule Network Analysis that is used to determine the amount of flexibility that exists in regards to the scheduling of a particular and specific logical network path with the network of the project schedule. The amount of flexibility within the scheduling here can also be referred to by the term “Total Float“ or "Free Float".

It is a method of calculating the overall duration of a project by taking account of the sequence and duration of activities that make up the project / programme and the logical inter dependencies between the activities.

The method is a mathematical model of the project which calculates the earliest and latest start and finish dates for activities, their float and the critical selection of activities that must be completed on time.