... one can infer a more precise tile size from those! Anyone got the relevant thread link?
Assuming gravity works like real world gravity and you can invent a time unit (obviously not linked to the dwarf mode calendar, which moves too fast for this), then a choice has been made. It wouldn't make any fewer dragons fit in the tile though. I think for the purposes of the minecarts it turned out to be 2m x 2m x 3m with 10 clicks / second, but it isn't that important or far-ranging in effect.
So, in surface area terms, a single fortress tile / square is 2 x 2 = 4 m^2. This converts to the following area measurements (rounded):
* nanoWales: 5.2 squares
* Square Perch / Square Rod: 6.3 squares
* Rood: 253 squares
* Acre: 1,012 squares
Traditionally the amount plowable by one man and one ox in one day; a furlong (40 rods) by 4 rods
* American football (handegg) field: 1,338 squares
* Joch: 1,439 squares
* FIFI football (soccer) pitch: 1,785 squares
* DF Embark Square (48x48 fortress squares): 2,304 squares
* Hectare: 2,500 squares; 1.09 embark squares
* Oxgang (15 acres): 15,180 squares; 6.6 embark squares
This was the traditional amount tillable by one ox in a single plowing season
* Survey Quarter-Section (160 acres): 161,920 squares; 70.3 embark squares
This was the amount traditionally allocated in the US for a single settler (family) in new lands; about 70.3 embark squares, or a bit over an 8x8 embark
* DF Region Square (16x16 embark squares): 589,824 squares; 256 embark squares
In very round numbers, a DF region square then roughly corresponds to a US survey section; 1/36 of a township
* City of London (traditional, aka "the square mile"): 725,000 squares; 315 embark squares (about an 18x18 embark);
* Manhattan: 14,875,000 squares; 6,456 embark squares; 25 region squares
* Washington, DC: 44,250,000 squares; 19,205 embark squares; 75 region squares;
* DF Pocket World (17x17 region squares): 170,459,136 squares; 73,984 embark squares; 289 region squares
* DF Smaller World (33x33 region squares): 278,784 embark squares; 1,089 region squares
* Rhode Island: 784,750,000 squares; 340,603 embark squares; 1,330 region squares
* DF Small World (65x65 region squares): 1,081,600 embark squares; 4,225 region squares
("Three times the size of Rhode Island")
* Wales: 5,199,500,000 squares; 2,256,727 embark squares; 8,815 region squares (~94x94)
* DF Medium World (129x129 region squares): 4,260,096 embark squares; 16,641 region squares
("Nearly twice the size of Wales")
* DF Large World (257x257 region squares): 16,908,544 embark squares; 66,049 region squares
("Nearly half the size of Germany")