What size storage unit do you need
Researched and written by Ashley Davis · Reviewed by Emily Johnson · Last reviewed August 2026
The size you need is decided by the largest furniture rather than by the number of boxes, so work it out in that order. List the four biggest pieces, count the boxes, then match against the standard footprints: 25 square feet for a closet's worth, 50 for a studio, 100 for a two-bedroom, 200 for a family house. Add one size if you need to walk into the unit during the stay, and subtract nothing for stacking, because stacking is already assumed in those figures.
What do you measure first?
The four largest pieces, because those set the floor plan and everything else fills the gaps around them. In most homes they are a sofa, a mattress set, a refrigerator and a dining table or a wardrobe. Write down the length and depth of each. Two of those side by side already span the ten-foot width of a standard unit, which is why a home with more than four large pieces rarely fits a ten by ten however carefully it is loaded.
How do you convert boxes into space?
Count the boxes by size and stack them mentally against a wall. Standard cartons stack four or five high within a normal reach, so a wall run of ten feet takes roughly forty medium boxes in two rows of depth. Boxes are the flexible part of the load, which is why they are counted second: they go where the furniture is not.
Which footprint does that come to?
Match against the five standard sizes. Under 25 square feet of contents goes in a five by five. A studio or single bedroom fits 50 square feet, which is a five by ten. One or two bedrooms with appliances fit 100 square feet, a ten by ten. Two or three bedrooms need 150. Three or four bedrooms need 200, a ten by twenty. The unit sizes page sets out what each holds in more detail.
When do you need the next size up?
Add one size whenever you will open the unit more than once. A walkway costs roughly two feet of width down the length of the unit, which on a ten by ten is a fifth of the floor. If the unit is a single load and a single unload, skip the aisle and pack wall to wall, since the only cost is that nothing is reachable until the end.
How do you check the answer before you commit?
Ask to see an empty unit in the size you have arrived at and stand in it. A footprint on a website is an abstraction and a real unit is not, and the difference between a ten by ten and a ten by fifteen is obvious in thirty seconds standing in each. Most contracts are month to month, so a unit that turns out to be wrong can be changed, but moving between units is a second load of the same furniture.