What Are the Average Dimensions for a Trundle Bed?

Trundle bed frames, which contain a set of casters to make rolling easier, are generally slightly smaller than a regular bed to enable the trundle to fit beneath the other bed frame. People with back issues may have trouble using a trundle bed, since it rests close to the floor. Trundle beds are designed to save space when not needed, while making it easier to provide extra sleeping space.