No, the Litter-Robot does not have a weight limit. Size and weight often have little to do with whether a cat will adopt the Litter-Robot or not. When we describe which Litter-Robot model is best for cats of a certain size, our recommendation is based on the size of the globe (litter bed area and height of internal space) and the size of the entryway. Our definition of a small cat is 2-5 kilograms; medium cat is 5-7 kilograms; large cat is 7-10 kilograms; and extra large cat is any cat that weighs more than 10 kilograms. Again, the Litter-Robot does not have an upper weight limit, so whether or not the Litter-Robot will be comfortable for a large or fat cat is up to the individual. The Litter-Robot Open Air was made with larger cats in mind. It has a larger entryway and expanded litter bed area to accommodate larger cats.