Ds1's room is about 3m squared. DS2's is slightly bigger, maybe 3m by 3.5, and the twins room is the same (although eventually boytwin will share with DS2 and girltwin will have this room to herself). The smallest room is absolutely fine as a bedroom size, enough room for a single bed, chest of drawers and a bookcase. There will be a built in robe in there soon too.