Looks like Excel is treating your entries as text.

Format the cells as numbers with two decimals. Do you get numbers in the
form 0.nnnn? If not then you do not have time in the cells.

Just to see how the sum works enter 4:36 and 3:04 in two cells of a new
worksheet and sum them up. You should get 7:40...

"Marta" wrote:

Hi,
I'm trying to add time entries using the SUM formula but I get blanks as the
result. My columns are about 20 cells long and contain anywhere from 1 to 20
entries at anyone time. I formatted all cells using [h]:mm:ss and it still
comes up blank.
Here's what I'm working with:

Date Total time
10/1/2008 4:36:33
10/2/2008 4:58:51
10/3/2008
10/6/2008
10/7/2008
10/8/2008
etc.


I want to sum up the "Total time" column. I used the following formula but
get nothing but a blank cell: =SUM(E217:E218)

Thanks,
Marta