Need help in Planned % Calculation

Hi Malarvizhi_P_R, I'm not entirely sure whether I understood your request correctly but did you mean something like this:

Planned % = 
VAR StartDate = SELECTEDVALUE(DimProjects[TargetStart])
VAR EndDate   = SELECTEDVALUE(DimProjects[TargetEnd])
VAR TodayDate = TODAY()

VAR InvalidDates = ISBLANK(StartDate) || ISBLANK(EndDate) || EndDate <= StartDate

VAR TotalDays = DATEDIFF(StartDate, EndDate, DAY)

VAR ElapsedDaysRaw = DATEDIFF(StartDate, TodayDate, DAY)

VAR ElapsedDays =  MAX(0, MIN(ElapsedDaysRaw, TotalDays))

RETURN
IF(
    InvalidDates,
    BLANK(),
    DIVIDE(ElapsedDays, TotalDays)
)

I assumed that you meant to calculate the percentage of how far along you are today compared to the Start- and EndDate and also added a check whether the Start- vs EndDate are valid or not. If you meant to check based on a third column that has the current status-date rather than using today as a reference-date you just need to replace the Today() with the selection for the column you want to use => then I would recommend to add a fallback in case that column is blank though, e.g. add another " || ISBLANK(TodayDate)" or use today() in the definition of the TodayDate-variable.

Btw this bit:

VAR ElapsedDays =  MAX(0, MIN(ElapsedDaysRaw, TotalDays))

 is just to ensure that the percentage stays between 0 - 100%. If you want to get negative percentages (e.g. current date is before the official project StartDate) or want to show >100% (e.g. currently 260% for Project 10) you just have to replace this part:

RETURN
IF(
    InvalidDates,
    BLANK(),
    DIVIDE(ElapsedDays, TotalDays)
)

with: 

RETURN
IF(
    InvalidDates,
    BLANK(),
    DIVIDE(ElapsedDaysRaw, TotalDays)
)

which will give you: