Due these little bastards have unlimited space in them so you can fit anything you want in them as long as you can open the bag enough?

Or do these have limited planar space?

Just curious.

The bags have as much space as the game mechanics give you. That is, you can only store so many space 'units' in your bag of holding.

Perhaps I should rephrase,

Does the bag of Holding actually give you access to another plane?

Hello. These are the forum rules. I'm going to go read them now.

Thomas_Not_very_wise Does the bag of Holding actually give you access to another plane?

A 7x5 square plane, which is extremely useful for storing stuff in (and not much else).