What are fields considered while calculating critical path in MS project? RRS feed

  • General discussion

  • Hi ,

    I'm new to the MS Project.

    I want to know about critical path and it's calculations.

    What are the key fields are used in critical path calculations?

    Is it possible to calculate critical by manually same to MS Project calculations. If it is possible, please provide details and reference links.



    Thursday, May 5, 2016 9:59 AM

All replies

  • Hello,

    It is calculated based on the free slack. Default is 0 days, see this link:


    Paul Mather | Twitter | | CPS | MVP | Downloads

    Thursday, May 5, 2016 10:36 AM
  • Paul,

    A minor technical correction. I think you meant to say it is calculated based on Total Slack, not Free Slack.

    Thursday, May 5, 2016 2:38 PM
  • Thanks John - correct Total Slack! :)

    Paul Mather | Twitter | | CPS | MVP | Downloads

    Thursday, May 5, 2016 5:02 PM
    1. Project designates an individual task as "Critical" if its Total Slack is less than the threshold you set in the scheduling options.  The resulting collection of tasks might be referred to as the "Critical Path" by some users, though Project itself does not use that term.  It can meet one definition of "Critical Path" under certain conditions.
    2. Total Slack is nominally selected from Start Slack or Finish Slack (they're typically the same), though I've not found a situation where Total Slack did not equal Finish Slack.  Start and Finish Slack are themselves the differences between the Late Start/Finish dates and Early Start/Finish dates.  These differences are computed according to the effective Calendar for the task.
    3. Early and late dates come from the forward pass and backward pass through the schedule network, respectively, with adjustments for constraints, deadlines, actual dates, and resource leveling. Some of these adjustments will depend on your schedule options.
    4. If you find yourself questioning the basis for a Total Slack calculation, start by comparing Late Finish and Early Finish fields for the task.  These can be affected by predecessor and successor logic as well as constraints, deadlines, actual dates, and resource leveling.

    You can manually calculate any schedule you want using the "precedence diagramming" ("Activity-on-Node") version of the "Critical Path Method".  Such an exercise is pointless for other than purely academic purposes, in my view, as Project does a fine job.

    Friday, May 6, 2016 12:59 AM