Re: Using a calculated field and DIFFINDAYS() to exclude weekends?
Hi @sammvarley .
Calculated columns with Date columns are currently problematic in Dataverse.
We could in theory use something like below to obtain the date difference between two dates excluding weekends:
RoundDown(DateDiff('Date Column End','Date Column Start', TimeUnit.Days) / 7, 0) * 5 +
Mod(5 + Weekday('Date Column Start') - Weekday('Date Column End'), 5)
Although the functions applied above are supported (RoundDown, Mod, DateDiff, Days, Weekday), attempting to apply this to a PowerFx formula will return the following error:

This is due to the lack of support at present for the localisation of Dates in Dataverse. Time zone conversion is not yet supported in calculated Dataverse columns.
You can find detailed information about this here:
http://powerappsguide.com/blog/post/dataverse-formula-columns
As an alternative, I would suggest using Power Automate to do achieve this.
------------------------------------------------------------------------------------------------------------------------------
If I have answered your question, please mark your post as Solved. Remember, you can accept more than one post as a solution.
If you like my response, please give it a Thumbs Up.