Days Display in Years

Let's say you store your number of days in the [Number of days] measure. Here's one way of doing it:

Days in years = 
VAR Days = [Number of days]
VAR Years = ROUNDDOWN(Days/365,0)
VAR Months = ROUNDDOWN((Days - Years * 365)/30.5,0)
VAR sYear = IF(Years = 1, "", "s")
VAR sMonth = IF(Months = 1, "", "s")
VAR YearPart = IF(Years<1,"",Years & " year" & sYear & ", ")
VAR MonthPart = IF(Months<1, "", Months & " month" & sMonth)
RETURN IF(AND(Years=0,Months=0), Days & " day" & IF(Days=1, "", "s"),YearPart & MonthPart)

Sample output: