Task types and scheduling in Project

 Jul 03, 2015

One of the hardest aspects of working with Microsoft Project is being able to understand the relationship between the three main units of measurement.

Correctly understanding these three units of measurement and how they interact with the types of tasks that exist is key to ensuring your scheduling works for you instead of you working for it.

In this post, we will identify the information we need to understand in order for our scheduling to be successful.

Duration, Work and Units

  • Duration = Work / Units (D = W/U)
  • Work = Units * Duration (W=D*U)
  • Units = Work / Duration (U=D/W)

Units represent the time spent on an activity. For example, if one person commits to spending all their time on a task and another person commits to half their time, the units for both would be 150% (or 1.5). As another example, if you had 12 tradesman allocated to a task, the units would be 1200% (or 12). Here are some variations on entry of duration, work and units.


Task Type Behaviour


The above table assumes effort driven is not selected.

With effort driven selected, the Project behaves differently when calculating. Rather than recalculating work, it assumes the work will remain the same throughout. This means that for the most part, 2 parts of the scheduling formula (W = D * U) will remain the same. So with Effort Driven selected the following occurs:


So to summarise the changes:


Hopefully, you now have a better understanding of the relationship between the units and types of tasks. Happy scheduling!

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About the Author:

Steve Wiggins  

Steve is a highly experienced technical trainer with over 10 years of specialisation in Software Application Development, Project Management, VBA Solutions and Desktop Applications training. His practical experience in .NET programming, advanced solution development and project management enables him to train clients at all levels of seniority and experience. Steve also currently manages the IT infrastructure for New Horizons of Brisbane, providing him with daily hands-on experience with SCCM, Windows Server 2012 and Windows 8.

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