A bit more robust in case there aren't 12 cells before

=SUM(INDEX(1:1,1,MAX(1,COLUMN()-12)):INDEX(1:1,1,MAX(1,COLUMN()-1)))

--
HTH

Bob Phillips

(replace somewhere in email address with gmail if mailing direct)

"Bob Phillips" wrote in message
...
=SUM(INDEX(1:1,1,COLUMN()-12):INDEX(1:1,1,COLUMN()-1))

--

HTH

Bob Phillips

(replace xxxx in the email address with gmail if mailing direct)

"Mopechicken" wrote in message
...
I need to sum the preceding 12 cells in a row within excel - regardless
of
the fact that some columns will be added in front of this cell with the
formula. I want the formula to "float" just not sure how to accomplish
it?