One way (assuming the cells without data are blank):

=AVERAGE(A1:L1)*12

In article ,
BillyRogers wrote:

I need a formula that totals 12 cells in a row ( the row is monthly sales)
for an annual total.

However if the row doesn't have a full 12 months worth of data I need to
estimate the annual sales by taking an average of the available months and
multiplying them by 12.

(the available months will vary on each row- some may have only the first 3
months or 7 months etc)

Thanks for any help on this.