Is there a way for MS Project 2007 to calculate durations based on a give time/part and total number of parts. For example:

A manufacturing process can process 1 part every 30 sec and we want to build 100 parts. This would take us 50 min to complete.

If I have a series of processing steps listed as tasks in project, can I calculate the duration of each task based on a given quantity of parts to build.

The goal is to create a template and have it basically auto calculate the build time for a given build size for each build cycle. Project would be much easier to manage the build cycle than trying to do this in say Excel but the auto calculations are a must.


  • 1
    I suspect that I could program this custom calculation into project, but it would be far easier to do the job in excel.
    – MCW
    Aug 14, 2014 at 11:18
  • Agree with Mark. This is a spreadsheet job. Not only can you build your calculations, but you can also add variability and conduct simulation tests with a simple add-in. Aug 16, 2014 at 11:04
  • The calculation part of this would be easier in Excel, but I still need the project planning/tracking features of MS Project (gantt chart, timeline, resources, etc...).
    – Richard
    Aug 18, 2014 at 15:14
  • We perform prototype and validation builds of varying quantities and need to provide build plans for each build cycle. We know the manufacturing numbers and would like to automate the planning some.
    – Richard
    Aug 18, 2014 at 15:15

1 Answer 1


The Duration field cannot be customized by calculations. However, there are spare number fields (Number1 through Number10) where you could perform the calculations and copy/paste into the Duration field. If you have some skills with VBA you could automate the copy/paste process.

  • I have looked at the custom fields and was able to do the calculation, I just couldn't get the result into the "Duration" field. I'll try some VBA and see how that goes.
    – Richard
    Aug 18, 2014 at 15:17
  • Using a VBA script was the way to go. I added some custom fields, a Do While Loop, checked some conditions and works great. Thanks all for the help.
    – Richard
    Aug 18, 2014 at 21:43
  • Great. Glad to hear you've found the solution.
    – JulieS
    Aug 19, 2014 at 17:50
  • Can you please let me know how you got the VBA. Mar 30, 2019 at 7:20

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