I figured I'd put this in business in hopes that those of you who use excel a lot could help. I want to create a prospective 2-5 year site growth graph that I can tweak based on starting users and rate of increase. The thing is, the only formula I know is the compound interest one, which I believe is exponential. I think site growth is some sort of inverse exp or log because I assume it's going to grow at a really fast percentage at first, and then start tapering off to a more steady level. For example, i think site traffic would probably go like this. month impressions % increase 1 500 - 2 995 +95% 3 1890 +90% 4 3496 +85% ... 22 200,000 +5% 23 210,000 +5% 24 225,000 +5% etc Code (markup): Now, of course, I could just manually play around with the numbers, but how can I make the percentages decrease on a smooth exp or log scale based on the one before it. (and since the impressions are current + current*% they would increase correctly)