How big is the World of Warcraft in real world geographic terms?

Let's specify this question^[a] a bit:

I'm not interested in how big the continents or whole world are supposed to be, but rather in an approximation (or measurements) how big all the zones^[b] combined are on all the continents together.

That is, map size in km² / mi² / real world comparison when comparing the zone sizes with the avatars size and how long it takes one to run through.

I would appreciate answers that are backed up by some research. Educated guesses are welcome too, but please try to motivate how you arrived at your guesses. :-) Thanks!

_{[a]: Note that I "stole" this question title from a question here, and I found another random q here that doesn't give a satisfying answer either.}

_{[b]: I never played that much. Are they called "zones"? If not, feel free to edit.}

Great question :)

I wondered it myself and googled it before trying, so here is a good discussion on the issue;

http://tobolds.blogspot.com/2007/01/how-big-is-azeroth.html

And a mentionable and scientific! approach in a comment :)

Mages can use "blink" to jump forward 20 yards. So, I blinked forward five times, ran back and measured the distance a few times. Averaging it out, you run 100 yards in 14.15 seconds. 100yards / 14.15 seconds = 7.067 yards/sec Three yards to a foot, means 21.201 feet/sec. Which works out to 14.46 MPH. Meaning, in 18 minutes 35 second you actually ran 4.48 Miles. So, lastly, 4.48 miles / 3.7 * (6.4 miles on each side [The square root of 41 square miles]) = 7.75 Miles on one side. 7.75² = Kalimdor is closer to 60.1 Square Miles

For ref: Manhattan is 20 square miles

read all the comments, they made quite a discussion on the issue..