Guest beds are available in single, double, and queen sizes. But they will differ from each other in the size when they are folded up. Guests beds that come as foldable sofas will look like a large sofa when folded up. Depending on the size, they might convert to become a single bed, double bed or a queen-sized bed. It is extremely rare for guest beds to come in sizes larger than that. This is because the primary reason for choosing a guest bed is to save space. So, most people will prefer to have the smallest one they can have.