Whenever you have to calculate the distance between two dates, you can simply subtract two dates and DAX in PowerPivot will give you the answer. However, in case you want to calculate the difference in terms of working days you have to instruct your data model about what a working day is.
If you want a practical guide about how to do calculations based on working days in PowerPivot, read this post from Alberto Ferrari that explains the basic concept to get this job done.
Do you want to touch the real Karma of PowerPivot? Don’t miss the opportunity to follow one of the workshops I and Alberto are bringing all over Europe in the next few months.
You can find more info on www.powerpivotworkshop.com. Hope to see you there!