Well, that depends on what size :-))) When it comes to terrarium size, and large snakes, you can imagine that a 10 foot python, likes to move freely, and not be cramped into a small tank, only stretching when handeld. On the other side the 17 feet long female will seldom lay out in a line...As I got more info on tanksizes, I found out that there are certain things that you might take into mind, when building your cage, since there are some things with pythons that need to be done SAFELY , and,  in a small cage, there's no room to manouvre, whilst in a room filled cage, the snakes CAN be territorial. So there has to be a middle way, upthat the snakes have room, and it's safe to handle them... It has been written that a good terrarium size is something like this : if you take a diagonal size of the enclosure, that is minimally 0.7 x the length of the ( matured !!) snake, you should be OK.

All my terrariums have a 0.9x and it will suit them just fine. Also I remodel the inner space of the terrarium sometimes, so they can go out exploring :-)