4x2x2....4 high! We use real glass and call in the dimensions to a glass company. Plexi will dull and scratch easily and is a bit more expensive than actual glass. We don't use what you can find at Home Depot as that is really really thin and not a safe piece of glass. If you go on DIY cages....and search me you will find another cage that my husband did with 2 cages (one on top of the other). He framed in the doors and it actually blows this one away!!!