Hey, I ordered this chainmail in a size 4!

[The Souljourner]

RAW: Armor and weapons do not resize to fit wearers/wielders of other size categories.

Actually, it's unclear about armor. There's a line in the DMG that says something about not letting a character's choice of race restrict the armor he can wear, and that, in general, when a PC picks up some magic armor, he should be able to wear it, unless it's a special armor made for a specific race. It doesn't specifically say it will resize to fit different sizes, but it doesn't rule that out either.

I think I most people assume that magic armor doesn't resize to fit different sized wearers, but resizes enough such that races of the same size can wear the same magic armor.

-The Souljourner

 

[Bront]

I like the resizes down only idea for weapons and armor. The problem I have if weapons and armor don't resize, is that it tends to restrict things that I give out too much. In general you're going to find less small items, which makes it unfortunate for the smaller characters. And they are already at enough of a disadvantage.