What It Does
This formula will return the percent of the month completed for a given date.
How It Works
DAY(Date) will return the day part of the given Date. In our example DAY(“2017-09-10”) returns a value of 10.
EOMONTH(Date,N) will return the last date in the month which is N number of months before or after the Date. If N is 0 then this will be the last date in the same month as the given Date. In our example, EOMONTH(“2017-09-10”,0) results in “2017-09-30” because this is the last date in the month of September. We then use the DAY function to return the numerical value of the last day of the month. In our example DAY(“2017-09-30”) results in the value 30.
We then get the percentage of the month completed by dividing the day part of the given Date by the day part of the last date in the month. In our example, this is 10/30 which results in 33.3%.