Calculating Duration (showing overages by number of days)



I am trying to run a duration formula based on the start and end dates on a project and the estimated dates. The estimate dates are how long we think the project will take, the start and end are the actual dates for the projects life. I also need to factor in a break down of each month, so in other words duration with overages for the month of January 2023, February 2023, etc.

Any guidance is greatly appreciated!

Thank you,




  • Ipshita
    Ipshita ✭✭✭✭✭✭

    Hi @tim.curtin

    I am assuming you have columns for -

    1) Start Date

    2) End Date

    3) Target End Date (this is your estimated project completion date)

    Now, your duration formula for calculating project timelines would be -

    1) Target End Date - Start Date = Estimated days for project completion

    2) End Date - Start Date = Actual days for project completion

    I am adding some formula examples below for your help.

    If you need to factor in working days for each month, that excludes the weekends - try using the NETWORKDAYS formula from the below chart or use NETDAYS if you don't need to exclude weekends -

    Hope this helps! Let me know if you are able to get your desired results.



    Ipshita Mukherjee

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