As of the 28th of January 2017, the average page size on this Wiki is roughly 1432 bytes long.
The largest page, Skills List stands at 50146 bytes while the smallest page, Walpurgis' Spirits "weights" in at 0 bytes. The most average page belongs to King's Judgement at 1433 bytes.
The test was done by copying http://atlantica.wikia.com/wiki/Special:ShortPages?limit=5000 to the regular expression tester at https://regex101.com The regex expression used is: .+\[(\d+),?(\d+)? bytes\] and the substitution string is $1$2
The total of all 2410 pages is 3452133 bytes or 3,45 MB.
In comparison, the English Wikipedia's 5 million pages database is around 11,5 GB big (2015 numbers), with an average page size of 23000 bytes (0,023 MB).