The vast majority of trundle beds are twin size, which means one person can sleep on each mattress comfortably. This is great for most applications, but for accommodating more than one person on each mattress, or for allowing more sleeping space for one person on each mattress, a full trundle bed is a better choice. A full trundle bed will feature two full size mattresses, which are larger than twin but smaller than queen mattresses. Choosing the best trundle bed in this size starts with determining your overall needs.
If, for example, you need a full trundle bed that will not only accommodate sleepers, but also offer storage space, you will need to consider a model that features drawers in the lower bed. This usually means the upper bed will be raised higher up off the ground than other models, but the advantage is that the lower bed will feature a sleeping surface as well as storage for clothing, blankets, or other items. Such models usually do not feature pop-up capabilities; in other words, the lower mattress will not pop up to a normal height after it has been moved out from underneath the upper mattress.
When accommodating older adults or people who have difficulty bending, it is a good idea to consider a pop-up full trundle bed. The lower unit can be slid out from underneath the upper unit, and once it is clear of the main unit, the lower bed can be popped upward and locked in place so the mattress is at a normal height. This makes getting into and out of the bed much easier, especially for people who have difficulty stretching. In some cases, the popped up mattress can even be flush with the main frame and mattress, creating one large sleeping surface.
Remember to consider the size of the room in which the full trundle bed will be placed. This may have an impact on whether the full size bed is appropriate at all. While one full size bed may fit well in a space, it may be difficult to slide out the lower bed and use it comfortably in the same room. If this is the case, a twin size trundle may be more appropriate. Take careful measurements of the space to figure out how much clearance you will have for walking space when the trundle bed is completely rolled out.