Convert cell format from custom h:mm to minutes

I have played around with the format custom h:mm. I believe you are using the wrong format. This is for time only. Time can either be displayed in 12 hour time with AM/PM or it can display in military time 00:00 - 23:59. If you enter in a time that is outside the normal range, that is when you get the fictitious date.

Eg)

8:00 = 8:00AM
20:00 = 8:00PM

If you enter something outside that range, that is when you get the date issue

Eg)

34:00 That is not a legal time, therefore, it gives you that strange date and time. To you it may look like 2,040 minutes, but the computer is looking for a legal time to display.

24:65 To you this may look like 1,505 minutes, but the computer again can not give you a correct time because you have went outside the time parameters.

What I would do is use two seperate columns to display your numbers, then you could calculate the minutes with out any problem. I have attached a small worksheet for you to look at so you can see how you could reformat your worksheet.