I have a new calf warmer that is 4 feet tall and 4 feet wide. I bought it last year and then I sold my cattle. The interior floor base is 4 feet wide and 32 inches from front to back. This calf warmers is built mostly out of painted plywood and is quite durable. The front side has a sliding door that has a 3 feet wide by 26 inch tall opening so it makes it easy to get a calf in and out. It also makes it easy to change heat settings. There is also a small door on the top that is used as a peek whole and for venting. I know many farmers that have this same calf warmer and they all like them. It does have a heater in it already. If you are interested or have any questions please call Eric Becker at 701-321-1089 Thanks.