Party Level
Party Level represents the general strength of a group of Player Characters (PCs) based on the level of each of it's members. It is used to calculate the Experience that each member of the group receives from a combat encounter. Party Level can be determined by the following Equation:
Party Level = Sum of Each PCs Level
Example
If you have a party consisting of five characters of 6th level, the party level for that group would be 30 (5 x 6). Alternative, if your five member party consisted of one 5th level, 2 6th level, and two 7th level characters, your party level would be 31 (5 + (2 x 6) + (2 x 7)).
Party Level is also useful for Encounter Design, allowing you to multiply the amount of experience you want each character to receive by the Party Level, in order to obtain a goal Experience total for an encounter.