Some guy calculated that Skyrim's overworld is between 5 square miles and 8 square miles in size.
Assuming a door in Whiterun is 8' tall and an Altmer is 6'5'', the following dimensions for Skyrim were found:
Width (East - West):
- 5.1 km,
- 3.2 miles
Height (North - South):
- 3.2 km,
- 2.0 miles
Longest Width (NW to SE):
- 5.5 km,
- 3.4 miles
Area:
- 14.8 km^2,
- 5.7 square miles
The method for finding these, a couple of different ways, and some other estimates for upper/lower limits appear below.
Full Answer:
I was surprised to find that I couldn't easily locate an official answer to this, or even a generally agreed upon figure. As such, I decided to have a go at answering it myself. The estimate I ended up with is quite rough, but I'm fairly pleased with the answer.
To make an estimate, a scale needs to be established. There are no definitely known sizes for things in Skyrim, even the people, but we can make sensible estimates on some objects and work from there. I began with the doorway of the Bannered Mare, in Whiterun. This doorway looks to be somewhat taller than most, and the tallest standard door size is 8 feet. To do a sanity check, make sure that was reasonable, I took an estimate to see how tall that would make my character; by comparison, my character is revealed to be 6'5''; as my character is an Altmer, tallest of the races, that doesn't seem too unreasonable.
[img]http://qph.cf.quoracdn.net/main-qimg-7c1b796573e39228a5be959ad7c8fabc[/img]
From there, I looked at the Bannered Mare as a whole, using the now known height of the door to make two more measurements, which I have labled A and B:
[img]http://qph.cf.quoracdn.net/main-qimg-b30e99ba06f709dcdc16208e3a48c9c4[/img]
Distance A is 10.2 metres, and B is 17.9 metres. But the Bannered Mare is far too small to be seen on a map of the overworld, so I needed another step. I timed how long it took my character to run the distance of A and B. By using the two different measurements, I hoped to minimise the prospects for error. To run A it took 1.8 seconds, while B took 3.4 seconds. Those both agree that my character runs at 5.6 metres per second.
Armed with this knowledge, I timed my character running a longer distance, outside of the walls of Whiterun, such that the distance would be visible on a full map of Skyrim. The distance I chose was between the crossroads and t-junction shown below:
[img]http://qph.cf.quoracdn.net/main-qimg-897906a263e0fde2520747fe7b6f4152[/img]
The time it took to run that distance was 42.0 seconds, telling me that the distance was 236.0 metres. Now, with a full map of Skyrim, that gives me a basis for measurement.
The best full map of Skyrim I could find was the following, which I marked with the basic measurements:
[img]http://qph.cf.quoracdn.net/main-qimg-4241950e486056b31f9255a6b1d7e453[/img]
EDIT: I did the kilometre to miles conversion wrong initially, this is now fixed.
Using a larger version of this map (to make accurate measurements easier), I found the following measurements:
Width (East - West):
- 5.2 km,
- 3.2 miles
Height (North - South):
- 3.3 km,
- 2.1 miles
Longest Width (NW to SE):
- 5.7 km,
- 3.5 miles
Area:
- 15.5 km^2,
- 6.0 square miles
It's worth pointing out that the area wasn't calculated from the width times the height, due to the irregular shape of the land. Instead, I broke up the area into a few approximate rectangles and took the measurements from those.
This estimate, due to the methods used, is obviously probably not totally accurate. If my initial estimate about the door is too far off, it could make it completely wrong, in fact. The sizes do seem rather small, but they do line up reasonably with my experiences of in game travel times. If anyone could suggest a better method, I would be interested, however.
UPDATE: After http://www.quora.com/The-Elder-Scrolls-V-Skyrim/How-large-is-Skyrims-overworld#'s comment, I did another set of measurements that eliminated the need for measuring time, and did the measurements entirely in the overworld, comparing distances. Hopefully this will decrease room for error, and avoid any potential problems with different scaling inside and outside of cities, which he helpfully pointed out were the weakest aspects of my first estimation.
First, I found a structure that would be easy to measure both in the game itself and in the in-game map, opting for as large as possible to make the map measurement easier. For this purpose, I selected part of the Whiterun outer wall, with this particular section being straight and easily visible on the map.
To determine the sizes of this piece of wall, I used the fact that my character's height was known from the measurement of the first door, at around 6'5'' or 195 cm:
[img]http://qph.cf.quoracdn.net/main-qimg-14df61190742b3a47d096302efa44d53[/img]
This gave me the height of the gate into Whiterun, which turns out to be almost exactly 4 metres.
Moving back away from the gate, I could then see the entirety of my selected section of wall, and use the known 4 metres to make a judgement on its length:
[img]http://qph.cf.quoracdn.net/main-qimg-a00e73e502f473c23bb891a2d34f863f[/img]
The width between the two corners is 27.8 metres. Comparing this to the overworld map, then, allowed to me once again get an estimate for distance C, the distance between the cross-roads and t-junction:
[img]http://qph.cf.quoracdn.net/main-qimg-a742f4a3ffaf2f01d3adb5b56d9f6e73[/img]
The new measurement for distance C is then 231 metres. This is just 5 metres different from my first estimate (around 2%), which is quite reassuring, as it would suggest that neither method is likely too wrong (though both are still based on the 8' door assumption). This difference of five metres doesn't make too much difference to the overall distances of Skyrim, though there is obviously some change and the area (being a multiple of two distances) is affected more noticeably. From this estimate, I find the sizes of Skyrim to be:
Width (East - West):
- 5.1 km,
- 3.2 miles
Height (North - South):
- 3.2 km,
- 2.0 miles
Longest Width (NW to SE):
- 5.5 km,
- 3.4 miles
Area:
- 14.8 km^2,
- 5.7 square miles
While it is likely this method of estimation is more accurate than my first attempt, I think both are still worth considering, so I have left my original estimation untouched. Again, if anyone has suggestions about other ways you could go about this, or improve the measurements, I would be interested to hear them.
UPDATE 2: http://www.quora.com/Mike-Barnard made a good point about idealized characters and how that might make people/doors taller than they are in real life. As such, I'll provide a couple of other estimates based off of his suggestions on what upper and lower limits might be on an Altmer's height. The method used is the second one (with http://www.quora.com/The-Elder-Scrolls-V-Skyrim/How-large-is-Skyrims-overworld#'s suggested improvements) with the different heights substituted in at the beginning. The heights used are:
Lower limit:
- 6 feet
- 183 cm
Upper limit:
- 7'6''
- 229 cm
This gave the following dimensions for Skyrim. First, the lower limit:
Width (East - West):
- 4.8 km,
- 3.0 miles
Height (North - South):
- 3.0 km,
- 1.9 miles
Longest Width (NW to SE):
- 5.2 km,
- 3.2 miles
Area:
- 13.0 km^2,
- 5.0 square miles
And now the upper limit:
Width (East - West):
- 6.0 km,
- 3.7 miles
Height (North - South):
- 3.8 km,
- 2.4 miles
Longest Width (NW to SE):
- 6.5 km,
- 4.0 miles
Area:
- 20.4 km^2,
- 7.9 square miles
So Skyrim is almost certainly between 5 square miles and 8 square miles in size.