Let's assume your data is stored in cells A1:A5.

=COUNTIF(A1:A5,"=12:00:00")-COUNTIF(A1:A5,"12:15:00")

This calculation may change the format of the cell to display time, so in
that case you'd need to change the format back to General (or whatever you
need).

HTH,
Elkar

"khux" wrote:

Hi guys,

I am trying to count the instances between 15 minutes periods.

For example my data is:

12:05:34
12:11:45
12:12:12
12:14:43
12:15:59

I want my function to calculate how many instances there are between
12:00:00 am and 12:15:00 am. (for the above data it would be 4).

Can anyone help me?

Thanks!

khux