Calcuating number of months between two dates

I have a form with two date fields. A start date and an end date. I need to calculate number of months but in kind of a different way. I need it to show how many calendar months and then take the remaining days and divide it by the number of days in that month. For example 01/01/19 thru 03/16/19 would be 2 months and 15 days. I would need the 15 days to divide by 31 days in March so the end result would be 2.48 months