Thread: [Solved] How does "fixed work" work?
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Old 10-20-2013, 07:28 AM
JulieS JulieS is offline Windows 7 64bit Office 2010 32bit
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Hello Sofia,

When you assign resources to tasks, Project will calculate one of the 3 variables:
  • You assign a resource to a task where Project only "knows" duration - Project will use the resource's maximum units and calculate the work based upon the equation: Duration * Units = Work.
  • You assign a resource to a task and you tell Project how much work it is - Project will again use the resource's maximum units and recalculate the task duration based upon the equation: Work/Units = Duration.
  • You assign a resource to a task and you have told Project both how much work and the task duration - Project will calculate the Assignment Units based upon the equation: Work/Duration = Units.
Task types (fixed work, fixed units, fixed duration) are used to control the calculation Project performs when you change one of the variables in the mathematics relationship between Work, Duration, and Assignment units in Microsoft Project. If after Project knows all three variables (Work, Duration, and Assignment units), you start changing one of the variables, that is where Task Type comes in. When you set a Task Type, you are telling Project which variable (work, duration, or units) you do not wish to change if you change one of the other variables.

For example:

If a task is Fixed Work:
  • If you change Duration - Project recalculates Assignment Units.
  • If you change Assignment Units - Project recalculates Duration.
  • If you change Work - Project recalculates Assignment Units.
If a task is Fixed Duration:
  • You change Work - Project recalculates Assignment Units.
  • You change Units - Project recalculates Work.
  • You change Duration - Project recalculates Work.

If a task is Fixed Units:
  • You change Work - Project recalculates Duration.
  • You change Duration - Project recalculates Work.
  • You change Assignment Units - Project recalculates Duration.
So, to your question:


If you have a task duration of 3 days - and assign a resource at 200%, Project will calculate 48 hours of work. However - assigning a resource at 200% will usually cause the resource to be overallocated if the resource's max units are set to 100%.


If you know how much work a task is, you can specify the work and Project will calculate the duration. If a task is 24 hours of work and your resources are only available 8 hours per day, the task duration should be 3 days.


I hope this helps.
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