Tasks Types in Microsoft Project can be a little tricky as far as understanding how updating one of the variables will affect the others. Microsoft Project uses 3 Task Types:

  • Work
  • Duration
  • Units

After setting the initial values, you may need to make updates to your schedule. When you update one of the variables listed above, how will project recalculate for the change?

You can use the following chart a reference as to what to expect when making changes to your assigned work, duration, and units.


Task Type Fixed Variable Changed Variable Recalculated Variable
Fixed Work Work Work Duration
Duration Units*
Units Duration
Fixed Duration Duration Work Units*
Duration Work
Units Work
Fixed Units Units Work Duration
Duration Work
Units Duration

*If the units are recalculated, then you will not see a change to the schedule, unless you are viewing the Peak Units. Peak Units is a timephased assignment field. When the Units field is recalculated the Assignment Units value stays the same and the Peak Units value is recalculated. Peak Units represents the maximum effort a resource is working on a given assignment in the current time period.

Using the Task Usage view or Resource Usage view, right click the timephased grid and select Detail Styles. Add Peak Units to the “Show these fields” box by clicking the “Show >>” button. Click the OK button to apply your changes.

Peak Units

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