What fits in 50 square feet.

A large moving box is roughly 18 x 18 x 24 inches, about 4.5 cubic feet. Twenty of them is around 90 cubic feet, under a quarter of the 400 cubic feet a 5x10 encloses. Boxes are never the constraint in this size; furniture is.

A bed set, a dresser, a nightstand and the boxes that go with them occupy roughly 150 to 250 cubic feet once stacked. That leaves working room in a 5x10, which is why this is the size most commonly quoted for one room.

A studio or dorm room is a bed, a desk, a chair, a small dresser and personal effects. That is a one-room load, and a 5x10 takes it. This is the practical dividing line from the 5x5, which takes overflow but not a whole room.

A full one-bedroom adds a sofa, a dining set and kitchen goods on top of the bedroom load, typically 350 to 500 cubic feet before you account for the aisle you need to reach the back. At 400 cubic feet gross, a 5x10 runs out. The realistic sizes are 5x15 or 10x10.

A king mattress is 76 by 80 inches, so 6 ft 4 in by 6 ft 8 in. Stood on its long edge against a side wall it is 6 ft 8 in tall against an 8 ft ceiling and 6 ft 4 in along a 10 ft wall. It fits, with the box spring beside it.

A queen is 60 by 80 inches and a twin 38 by 75. Both stand upright against a 10 ft wall with room to walk past, which is not true in a 5x5 where a queen leaves almost no floor.

A two-seat sofa is about 5 ft to 5 ft 6 in long and 3 ft deep. Turned on end it stands within the 8 ft ceiling and takes a 3 ft by 3 ft footprint, leaving most of the 10 ft depth for everything else.

A typical road motorcycle is 7 ft to 7 ft 6 in long and under 3 ft wide at the bars. That length fits the 10 ft depth and clears the roller door; it does not fit the 5 ft depth of a 5x5 at any angle. This is the single dimension that separates the two sizes.

The shortest cars on sale are around 8 ft 10 in long and 5 ft 1 in wide before mirrors. A 5 ft wide unit has a roller door narrower still, so the car cannot be driven or pushed in. Vehicle storage starts at 10x15 and is normally 10x20.

A bicycle is about 5 ft 9 in long and a walk-behind mower about 5 ft with the handle folded. Both lie along the 10 ft depth without blocking the door, and bikes hang from a wall if the operator allows fixings.

Volume is never the issue with these. The real question is whether the unit is climate controlled, because sealed compressors and electronics do not enjoy a Phoenix or Houston summer in an uninsulated drive-up.

A banker box is 15 x 12 x 10 inches, about 1 cubic foot. Twenty-five of them is 25 cubic feet stacked five high on a single pallet footprint, which leaves the rest of the unit for stock or equipment.