I get email saying: "The Snail Bowl holds more that the 500 you have on your web page. I know for a fact that during the big play off game last year the newspaper estimated the crowd to be at least 4,000, why they were lined up all along the fence."
The count I try to get is what I call the "Butt on the Bench" count. I don't care how many you can out on the "berm" or how many old men line the fence. The true capacity is how many butts can you get "sitting" in the bleachers. This is the simple method I use.
Lets say a small stadium has on the home side has 15 rows. The stands run from the 30 yard line to the 30 yard line for a total of 40 yards. Here is a good formula:
(Rows x Yards x 3) ÷ 2The two foot per person eliminates the need to take out for ramps, aisles, etc. I have used this and later compared to official capacities and it's very close.