Don’t know where to put this, but…
Assuming my calculations are correct, the total area of the largest possible DF world (including both land and water) is slightly larger than the State of Georgia in the United States of America.
Interesting... I count 129 x 129 world tiles on the largest map, each of which has a 16 x 16 grid to choose from. I did a 16 x 1 embark, and counted it to be 768 tiles wide. Which (assuming no buffer zones between world tiles) gives an approximate world measurement of 99,072 tiles. If 1 tile = 3 feet, that is 297,216 ft, or 56 miles. So a square with 56 mile wide edges, giving a total area of about 3,169 square miles. That's about 20 times smaller than GA, so my assumptions are probably inaccurate. I chose 1 tile equal to 3 ft because that's about the standard width of a door, and doors take up an entire tile.
I suppose 1 tile could be 10 ft rather than 3, since a lot can fit in there. That would produce an edge length of 187 miles, and an area of 35,207 sq miles. A buffer zone between each of the 129 world tiles of 2,360 ft (or 236 regular tiles) would make up for the 20,000 sq mile shortage in area. Assuming no buffer zone, a 13 foot wide tile (as the Dwarf stands on it) would give a total large map area of 59,500 sq miles.
Are you using the 1-tile is approximately x size method, or some kind of astronomical method? I'd be curious to see how the results compare between the 2. Also, my tile count is based on fortress mode, perhaps adventure mode could produce a more accurate count and eliminate the buffer zone uncertainty.