what is the formula for adding up time intervals?

[Guest]

i am trying to set up a way to add up how much time was spent on particular
sessions with my business using millitary time. for example person X logged
into a machine at 9:43 and logged out at 17:12. is there a way to calculate
this using excel?

 

[CaptainQuattro]

Col A = Start Time
Col B = End Time
Col C = Elapsed Time

A3 =9:43
B3 =17:12
C3 =B3-A3

C20 =SUM(C3:C19)*24

Select Cell C20 and Format > Cells > General

If start time is before midnight and end time is after midnight:

e.g. end time is 2:00 a.m.
enter end time as 26:00

 

[Ardus Petus]

Say login time is in A1, logout time in B1
='B1-A1)+(A1>B1)
format hh:mm

The +(A1>B1) copes with cases like login=23:00, logout=02:00

HTH

 

[Ardus Petus]

Typo:
C1: ='B1-A1)+(A1>B1)

C100=SUM(C1:C99)
format [h]:mm

HTH

 

[Biff]

Hi!

Just subtract:

Log out - Log in

A1 = 9:43
B1 = 17:12

=B1-A1

If the log out time might span past midnight:

A1 = 9:43 PM
B1 = 5:43 AM

=B1-A1+(B1<A1)

Or

=MOD(B1-A1,1)

Format as [h]:mm

Biff