Hello hclyde, The space available for a litter pan is 18" W x 18.25" D x 18" H. Alternatively if you remove the middle divider it opens the space up to 27.5" W x 18.25" D x 18" H. Thank you for your interest in Trixie Pet products.
Hello Christina, This item has inside dimensions of 29.5"W x 20.75"D x 20" H, and the side opening is 8.75" W x 10.5" H. Thank you for your question.
Hello Renea, Yes this has a recommended max weight limit of 40 lbs on the top of this item. Thank you for your question.
Recommend you not put in the center support unless you want to place heavy items on top.
If the divider is in place it is 18" x 18".