Calculate count based on date Range : count records if the current record date and previous records

Sort your table with the DiagnosisDateTime column.

Next, create this CC to ount the records within the 60 days window for each record

Within60Days =
VAR CurrentDate = 'Table'[DiagnosisDateTime]
RETURN
CALCULATE(
COUNTROWS('Table'),
FILTER(
'Table',
'Table'[DiagnosisDateTime] <= CurrentDate &&
'Table'[DiagnosisDateTime] > CurrentDate - 60
)
)

Then, create a measure to count the records based on the Within60Days :

CountWithin60Days =
SUMX(
'Table',
IF('Table'[Within60Days] > 0, 1, 0)
)

Puja_Kumari25 

so you have two tables? You need to compare the date between these two tables? why the 4th row is within 60 days?

i saw the dates are  3rd Apr and 8th Jul.

Thanks for the reply from AmiraBedh  and ryan_mayu , please allow me to provide another insight: 
Hi  Puja_Kumari25 ,

Here are the steps you can follow：

1. Create calculated column.

Test1 =
var _last=
MAXX(
    FILTER(ALL('Table'),'Table'[DiagnosisDateTime]<EARLIER('Table'[DiagnosisDateTime])),[DiagnosisDateTime])
return
DATEDIFF(
    _last,'Table'[DiagnosisDateTime],DAY)

Test2 =
COUNTX(
    FILTER(ALL('Table'),
    [Test1]>60||[Test1]=BLANK()),[id])

2. Result:

Best Regards,

Liu Yang

If this post helps, then please consider Accept it as the solution to help the other members find it more quickly

Thanks for the reply, we need to count 60 days in a group only. Like here there will be multiple composite keys in the table.  For the same composite key group, 60 days logic will be implemented, otherwise for different not.