"Gary" wrote:
I use the formula (a2-a1)-30

Use:

(a2-a1) - 30/24

assuming that A2 and A1 are entered in the form hh:mm or hh:mm:ss. In those
cases, time in hours is stored as a fraction of a day.


----- original message -----

"Gary" wrote in message
...
I am building a spreadsheet that show a start time and a finish time. I
then
want it to calculate how much over the allotted time was used if any. I
use
the formula (a2-a1)-30. 30 minutes are the allotted minutes so it looks
right
that this formula would give me the correct amount of minutes over. I get
the
###### error message on this and I can't find a way to get it to give me
the
correct time. If I take the -30 out of the equation it will give me the
total time. I can I get the total time minus the 30 minutes?