The Critical Path Length Index (CPLI) is a metric used to measure the relative efficiency to complete a milestone on time. It’s used to calculate and graphically display the Critical Path; longest series of scheduled activities to complete a project. CPLI is a USD(AT&L) tripwire metric.

CPLI = (Critical Path Length +/- Total Float ) / Critical Path Length

A Critical Path Length Index of:

• Less than 1 = the program will not achieve its baseline completion date without corrective action and the CPLI should be tracked to gauge the realism of completing the contract on time.
• Greater than 1 = the program schedule is running efficiently in relationship to the milestone
• Equal to 1 = desired efficiently ratio

Example:
Through April the supplier network schedule calculates a program critical path length of 720 work days (3 years) with 60 work days (3 months) of negative float from contract award to completion:

CPLI = [( 720 – 60) / 720] = 0.917

At present, the supplier’s CPLI of less than 1.00 indicates that program will not achieve its baseline completion date without corrective action and the CPLI should be tracked to gauge the realism of completing the contract on time.