Please help with time calculation

[Al]

I posted this question before:
I need to calculate in a cell the time duration when the user inters start
and end times in the following fashion:

Start End Duration
00:00 00:45 0.75
00:45 01:30 0.75

Start and End times must be in 24hr format. My problem is in the duration. I
am required to calculate the duration like the example above i.e. instead of
showing it as 0:45 min (00:00 (12:00 AM) – 00:45 (12:45 AM) = 0:45 minutes,
my client requires it to show as three quarters of an hour in decimal format
(0.75). how can I do that? I need the user to enter 00:00 and 00:45 then the
form will calculate the 0.75.

and got the following solution:
(B2-B1)*24

The Problem:
this works fine with most but not in the following case:
Start End
21:30 1:00
The answer I am getting is -20.5? it should be 3.5
any Idea.
Thanks
Al

 

[Mangesh Yadav]

=(endTime - startTime)*24
format as general

Mangesh

 

[Mangesh Yadav]

Sorry, hadn't read the compete mail. Use:

=(B1-A1)*24+IF((B1-A1)*24<0,24,0)

B1 is end time
A1 start time

Mangesh

 

[Al]

I used it and got the same answer "-20.5". did you try it?
I am subtracting 21:30 (start time) from 1:00 (End Time), it should be 3.5.
This is the answer I am looking for. I have my cell formated as general.
thanks

 

[Mangesh Yadav]

I am getting 3.5
Please check the values B1 is end time and A1 start time.

Mangesh

 

[Al]

Sorry, It works. thank you very much, you have been a great help.
Al

 

[Dave Peterson]

Another option would be to include both the date and time in the cell. This
would make it a little more robust--if you crossed two midnights.

 

[Robert_Steel]

slightly shorter option

=(B1-A1)*24+IF((B1-A1)*24<0,24,0)

=(B1-A1+(A1>B1))*24

hth RES