In your example a rolling 12 month average is the same thing as the average
-- given that you have only listed 12 months. Assuming your values are in
A1-L1, you could put =Average(A1:L1).

Art

"SamA" wrote:

I am trying to create a 12 month rolling average, example follows.

J F M A M J J A S O N D average
item 1 2 3 4 5 6 7 8 9 10 11 12 (rolling average)

thank you