How large does an oven need to be to fit a 18 lbs turkey? Can anyone tell me the interior oven dimensions needed to comfortably fit an 18 lbs turkey?

I've searched around on the internet, but seeing as Thanksgiving is an American holiday, where most people have large, built-in ovens, I haven't had much luck pinning down an answer.

I don't know much of anything about cooking or turkeys or ovens, and I am living in China where ovens are rare and the sand-alone ones you can purchase tend to be small (more of a large toaster oven than what we're used to in the states).
The oven in a standard 20" kitchen stove will accommodate a bird even as large as 20 lbs (9 kg).

The very detailed chart here, the pertinent details of which are replicated in the chart below, establish the standard dimensions of such an oven as 18 X 16 X 14.5 inches (46 x 41 x 37 cm).



In their downloadable Thanksgiving pdf, for a turkey as large as 20 lbs (9 kg) Williams-Sonoma recommends a 16 X 13 X 3 inch (40 x 33 x 7.5 cm) roasting pan. A pan of this sort is available with a rack which rises just above the bottom of the pan, as here and pictured below.



This kind of pan keeps height requirements down to roughly the height of the bird plus 3" (7.5 cm) above the bird, plus the standard 2.5" (6.5 cm) below the bottom rack. With 14.5" (37 cm) worth of oven height to work with and about a half inch space between the bird and the pan, that still leaves room for a bird 8" (20 cm) tall. (We won't expect the bird to be half as tall as the pan is long.) Meanwhile, an 18" (46 cm) oven depth accommodates a 16" (41 cm) long pan, and a 16" (41 cm) oven width a 13" (33 cm) pan width. Also, as seen here and below, the pan's handles fold down.



Now, none of this is to say that there's anything the slightest bit convenient about roasting so large a bird in so small a space. But it can be done. It should just be done with every whit of safety in mind.