Carole,the Royal Canin Urinary S/O comes in a large bag that is 16.5lbs. I usually buy 3 of them at once so I don't have to reorder so often. So far they last me about 6 months and this is with feeding 5 cats. I also usually buy 2-3 cases of the wet food and they last me a long time because Sunny and Storm are the main ones that eat this. So far all of my cats love the taste. I hope that Lexie will also love it. Good luck.:)