How do you convert a date to decimal?

For instance, let's say I have a date of 10/23/11. I want to convert this date to decimals. So 10/23/11 would be 9.7419 months in this calender year. How does one do this?

Assume your current date is in M3 and your start of the year date is in M2, then use this formula.

=MONTH(M3)-MONTH(M2)+(M3-DATE(YEAR(M3),MONTH(M3),1))/(EOMONTH(M3,0)-EOMONTH(M3,-1))

Format as a number with as many decimals you want.

Alan

With a date in A1 this formula should do it

=MONTH(A1)-1+DAY(A1)/DAY(EOMONTH(A1,0))

format as number

Awesome! I had almost the same formula using days, I was not aware I could do months as well. Very big thanks to both of you!