this is NOT exact, but is based on an average of hits on someone's site
"Your mileage will vary depending on the type of visitors that your site attracts, but those results are fairly typical. A Google AdSense ad tends to generate between $2 and $3 CPM on average. Here are some scenarios:
* If your site has 1,000 visitors a day and they read 3 pages per visit, you get 3,000 page impressions a day and make about $270 per month.
* If your site has 1,000 visitors a day and they read 5 pages per visit, you get 5,000 page impressions a day and make about $435 per month.
* If your site has 10,000 visitors a day and they read 5 pages per visit, you get 50,000 page impressions a day and make about $4,350 per month.
* If your site has 100,000 visitors a day and they read 5 pages per visit, you get 500,000 page impressions a day and make about $43,500 per month."
http://webkew.blogspot.com/2005/04/l...-you-make.html