counting numbers in different time intervals

I need to count records in each 8h (starting from first adequate hour) during day (6-22) and in each 0,5h (starting from first adequate hour) during night (22-6).There is attached example solved for two days in K column. Could you please help me?

Adequate hour is the first one during night (or day). For example if there is 21:50; 22:20; 22:25; 22:30; 22:50; 23:05; 23:15; 23:45 then the first adequate hour for night is 22:20 and from it I would have to start counting. Consequently I would have to count how many records is between 22:20 and 22:50; 22:50 and 23:20; 23:20 and 23:50. Intervals each day will be different. Using Your method I would have to type them manually each time. It would be easer to count them personally. Is there any other solution of the problem?

I know there must be some solution and helper column doesn't bother me but I still don't know what formula can be used in it.

The "problem" is how you define "adequate hour":

21:50; 22:20; 22:25; 22:30; 22:50; 23:05; 23:15; 23:4

In the above why is "22:20" selected as the "adequate hour"?

A simple count formula is ..

=COUNTIFS(B:B,">" &$E$1,B:B,"<=" &$E$2)

Where E1 is your "start time" and E2 is your "finish time"

How are E1 and E2 defined?

Adequate for starting count 8h intervals - green. Adequate for starting count 0,5h intervals - red. Intervals - yellow. I hope everything is clear now.

Please remove ALL merged cells as they are the source of many problems

I will type other data in this sheet. I merged cells because I know that sometimes I will need a place for more than one record. I can unmerge those cells but numbers of records can not change so there will be empty records under those specific cells that were previously merged.

0,5h=30min.
The adequate hour for day time (6:00-22:00) is the first one after 6:00. The adequate hour for night (22:00 -6:00) is the first one after 22:00.
Merged cells can be unmerged but there still will be empty spaces and the must stay.
I don't know if macro would be appropriate if so I would gladly use one but consider that I have never used any macro and that is why I prefer formula.

I mean that it should be use as the beginning of first interval during specific day and daytime.

You are devoting your time. I am really greatful for that and I understand that you can be busy with something else. I hope you will find a solution because I really need it and for me or even some other persons knowing excel better than myself the problem is to complicated.

The list is also for different days (dates) what to do?

Of course it is. The formula should count whole sheet not only one day. If there would have been only one day would not be needed.

What are you counting?

The number of records in B column in intervals.

It does not make sense (to me), Forget the word adequate, please.
You have two groups 06:00:00 - 22:00:00 day shift and 22:00:00 - 06:00:00 night shift?

Yes. In the first group interval has 8h and in the second 0,5h(30min). The problem is that first interval could start at different hour each shift. First interval during night shift could be 22:00-22:30 but only if there is record with 22.30 in B column. If there isn't it could start in first hour that occurs in in B column. It could be 22:05, 22:15, 5:00 or any other hour that is the highest in B column during this shift. All other intervals should be measured from it so when the first interval during night shift is 22:20-22:50 the second will be 22:50-23:20.

What about the half hours

Half a hour is the time of interval in shift from 22:00-6:00 while 8h is the time of interval in shift from 6:00-22:00.

I am sure the question makes sense to you but we have to understand it to be able to help, I am not going to try an guess what you want.
So please try and give a clear example with what you have and what you want

I have what s in A an B column and I want to to have number of records from B column during each interval.

I do not understand you list. why are there full hours missing?

This is a question that I don't understand.

full hours is that I miss one or two ??:00:00

Which column and row are you writing abut?

You want to count all the hours between 06 - 22 that have a record, so on the hour change add one. so all greater and equal to 6 and smaller than 22 for the 'day-shift'
You also want this to be done for the hour between 22 - 06 so all hours greater or equal 22 and smaller than 6 for 'night-shift'

That's correct but you must remember that day-shift is not one interval and night-shift also isn't. Day shift is the time that intervals last 8h and night shift is the time when the last 30min.

Now the half hours, is that the half hour after the counted hour?

Yes

so if the first record is 7:35 then I cannot count 30 minutes because 7:35 + 0:30 is 8:05 is this correct?

It would be if 7;35 would be during night shift when the interval has 30min but it is during day shift when intervals has 8h.

During the 'night-shift' there will be two dates, count as one or stop counting at 24 (23:59:25.9999) and restart for the next day at 00 ?

Count as one

With all these 'exceptions' I do think you will have to use a macro.

or many helper columns

I only would like to have it counted. Method is less important.