The Great Microsoft Project Calendar Mysteries Unravelled

The calendars in Microsoft Project are a complete mystery to some users of the application.  Examples of this are where you see the bars on the Gantt chart are not beginning at the start of the day, or a day extends over into the next day.  You might have put holidays in but not see them on the Gantt chart.  Project can be infuriating at times and this is definitely one of them.  Once you know the steps, though, its easy and our advice to clients is to consider saving templates that contain the setup you require for most projects and save yourself a great deal of work and also the risk of human error.

The calendars and start date provide the base on which to build your programme of work. Without that your schedule may be feeding you incorrect data and will no doubt prompt some questions from stakeholders.  For some projects not having the calendars calculating correctly can have a major impact on planned completion dates.  Beware however of overworking the calendars.  Sometimes near enough is good enough!  Is it critical to the schedule that we know that at 6.30am a task needs to start? Or that our working day is 7.5 hours rather than 8?  Sometimes the answer to this question is “Yes” and Microsoft Project can provide us with very detailed days and weeks both for the project, individual activities and resources.  In future posts I will delve into the calendars in depth, but before you commence developing your schedule you need to decide.  Read our Blog post on this (Microsoft Project Calendars – How Accurately Do Working Times Have To Be Set?) for a better picture of this. Remember that the length of the day in your calendars will impact your estimated durations if you change your calendars in the future.  If you forget to put in a holiday day this is easily remedied. If you do need to add in a holiday day don’t worry about its chronological order just put it at the end of the list of exceptions.  The next time you open up the calendar it will be in its chronological spot.

So here is the first part of this puzzle to get right.  You need to set up your working day in Options.  I think of this as the backbone of the Gantt chart.  We can lay different base calendars over this backbone which I will discuss in future posts.  When you go to the File tab, choose Options and then Schedule.  You will be presented with the window below and this is where you set up your start and end times.  Microsoft Project does not then calculate the hours per day and week you need to enter these taking into consideration the lunch break.  Don’t worry about morning and afternoon tea; nobody gets into that much detail.  If you want to set this calendar for all your new projects make sure you choose “All New Projects” in the Calendar Options box. Finally, choose OK and that’s Step number 1.

Next week I will talk about the base calendars.  Until then – happy scheduling.


Sue Buck is a Director of ProjectTMA Pty. Ltd. As well as being a senior Microsoft Project training consultant she works with clients to help them develop and report on their schedules and incorporate Microsoft Project into their project management methodology. For more information call 1300 363 822 or email her at


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