Meters to feet is easy, it's roughly just x3. Yards may not be common (yards are certainly common in sports, and sports are very popular), but three feet to th

Meters to feet is easy, it's roughly just x3. Yards may not be common (yards are certainly common in sports, and sports are very popular), but three feet to the yard is definitely commonly known. Centimeters might be harder, but in my experience Americans suck at estimating inches too, one American's "half an inch away" is another American's "two inches away." And the average American off the street would be hopeless if asked how many feet are in a mile. They'd actually have a better chance of giving you a kilometer->feet conversion than miles->feet. At least, I certainly would (without looking it up: 1 kilometer = 1000 meters ~= 1000 yards = 3000 feet, +10% fudge, approximately 3300 feet to the kilometer.) Anyway, my point in all of this is that if a pop-sci publication like Wired uses units like kilometers, it is unlikely that their American readers will be confused. They'll probably walk away from such an article with a casual understanding of the subject that is reasonably close to the casual understanding they'd have if the article used miles instead.