Measure the entire route
Measure from the floor to the lowest obstruction. Feet, central supports and crosspieces may lie farther inside and divide the available space. A container can enter at the edge and stop shortly afterwards. Check the full intended insertion depth.
Include lids, wheels and raised handles. Product dimensions may refer to different points, so compare descriptions carefully. A rug beneath the bed reduces clearance, and its edge also matters when pulling a box out.
Allow room outside the bed
A box needs to reach an accessible position for filling and retrieval. With little space between bed and wardrobe, a long container may come out only partway. A split lid may help in some cases but does not replace access to the contents at the rear.
Compare several short boxes with one long one. Smaller units divide contents and are easier to carry, but require additional gaps. A large box may use the area more continuously while becoming heavy when filled. Decide by intended contents rather than the largest quoted volume.
Match material to contents
Fabric cases, plastic boxes and other containers offer different dust protection and cleaning requirements. Choose something suited to the contents and the conditions beneath the bed. Clean, fully dry textiles present a different task from occasional shoes.
A transparent lid can aid identification, but may not be enough beneath a dark bed. A label on the outward-facing side reduces searching. Keep categories manageable so that the same box need not be opened for numerous unrelated objects.
Preserve cleaning access
Plan how dust will be removed underneath. Completely filled floor space makes this more demanding. Boxes should come out without routinely dismantling or heavily shifting the bed.
Follow the bed manufacturer's guidance on using the space beneath it and maintaining ventilation. A container that fits does not justify tightly filling every gap. If the contents are rarely used and hardly inspected, reviewing them may help more than adding another box.
