Will a full mattress fit on an old double bed?

No, a full mattress will not fit on an old double bed. A standard full mattress measures 54 inches wide by 75 inches long, while a traditional double bed typically refers to a full-size mattress. However, if the double bed frame is slightly smaller or designed for a narrower mattress, the full mattress may not fit properly, leading to overhang or inadequate support. Always check the specific dimensions of both the mattress and the bed frame for compatibility.