Using NOW() will cause your timestamp to update every time the sheet
calculates. If that's what you want:

=IF(A1<100,NOW(),"")

Otherwise, see

http://www.mcgimpsey.com/excel/timestamp.html

In article ,
"Brandon" wrote:

Hey,
I'm trying to use the IF function to create a time stamp in another cell
if the Logical_Test is true. I'm kinda at a loss. If anyone could help me
that would be fantastic.
Thank you so much.:)