Hi @Anonymous ,
Yeah, you are right. The DateDiff function would not consider 30 days for every month. If you would like the DataDiff function to consider 30 days for every month within your app, I afraid that there is no way to achieve your needs in PowerApps currently.
If you would like this feature to be added in PowerApps, please consider submit an idea to PowerApps Ideas Forum:
https://powerusers.microsoft.com/t5/Power-Apps-Ideas/idb-p/PowerAppsIdeas
As an alternative solution, you could consider take a try with the following workaround:
If(
Month(StartDate) = 1 || Month(StartDate) = 3 || Month(StartDate) = 5 || Month(StartDate) = 7 || Month(StartDate) = 8 || Month(StartDate) = 10 || Month(StartDate) = 12,
DateDiff(StartDate, EndDate, Days) - 1, // remove the difference -- 1 day
DateDiff(StartDate, EndDate, Days)
)
Note: Detect if current month has 31 days or 30 days, if it has 31 days, minus 1 day from the DateDiff(...) result.
Please consider take a try with above solution, check if the issue is solved.
Best regards,
