I keep searching for this post again, so I'm linking it here: Brendan Lally on map scales.
ok, currently one square holds one person, even if they stretch out their hands, they don't occupy more than one square. This therefore suggests that the squares are sides of at least 1 fathom (that being the distance of someone between their outstretched hands. This is consistant with a bed being 1 square. Given that one tick is about 1 second of game time (not real time), and that a player moves 1 square a tick at speed 1, this gives a walking speeed such that at speed of 1.0 a mile is covered in (1 mile is 8 furlongs, is 80 chains, is 880 fathoms) 880 seconds, or 14.7 minutes (which is about correct).
The indoor maps are smaller on the outdoor maps, it tends to be the case, that 1 square outdoors correlates to 8-12 squares indoors. If the indoor squares are 1 fathom across, then the outside ones are about 10 fathoms across. Or almost 1 chain (11 fathoms). Since the value of 11:1 is well within the range of values that are used, and since it is a round number. It seems reasonable to consider each of the world map squares to be 1 chain. All the more so since this is the size used for buildings, and buildings have in the real world been set out on a scale of 1 chain for a house.
“In the laying out of towns in Australia and New Zealand, most building lots in the past were a quarter of an acre, measuring one chain by two and a half chains, and other lots would be multiples or fractions of a chain. As a consequence, the street frontages of many houses in these countries are one chain wide — roads were almost always one chain wide (20.117 m) in urban areas, sometimes one and a half (30.175 m) or two chains (40.234 m).”
In game most roads are 1 or 2 squares wide, which also fits in nicely.
Furthermore, by adopting this standard, it means that 10 squares on the world map is 1 furlong, which gives a nice way to measure distances, because it is also about 1 screen (default is a map view of 11×11 IIRC). in the gtk2 client, it is about twice that, so you see one furlong in all directions.
Ooh, and it also makes the distance from scorn to navar about 9 miles (75 furlongs), which is a somewhat saner estimate than 1000's of miles. 9 miles says 'you /can/ walk this but probably don't want to do so very often'.