Format as [s] doesn't change the value, so you can't subtract a number in
seconds from that.
To convert 15:44:00 to seconds, multiply by 24*60*60 (converting from
Excel's days to hours, then minutes, & then seconds), & format as General or
Number.
--
David Biddulph

"Teethless mama" wrote in message
...
Format as:
[s]

"Michael Vestel" wrote:

I have collected time and temperature data. The time data is in time
format
(13:30:00 for example) the time data needs to be correlated to another
set of
data (images) that are time stamped in seconds (like 3456s). I know that
the
time of 1820s on my image correlates with 15:44:00 in the excell spread
sheet. I'd like to convert the 15:44:00 to 1820 sec and all other time in
the
column be appropriatly scaled. I tried subtractin 15:44:00 from all the
times, but that only works for postivive differences (times that are
after
15:44:00). In addtion, i dont know how to convert to seconds and then add
in
the 1820s offset. Can someone suggest somethign?