How to use the storage unit size calculator
- List what you plan to store. For each line enter the item, how many, and its length, width and height in inches. A bed, a sofa, a dresser and boxes are loaded as examples to edit.
- Check the usable height of the unit. Many are about 8 feet, but confirm with the facility.
- Set the share of the space you can fill. It allows for odd shapes and a walkway. The example 75% suits a mixed load, and a neater stack of identical boxes can go higher.
- Read the suggested size and the table of common sizes. Use Copy, Print or CSV to keep the result.
Formula
Volume of a line (cubic feet) = how many x length x width x height / 1,728
Floor space needed = total volume / share filled / usable height
Suggested size = the smallest unit whose floor area is at least the floor space needed
There are 1,728 cubic inches in a cubic foot. Dividing by the share you can fill adds the empty space that real loads always have.
A one bedroom load
A queen mattress of 80 x 60 x 11 inches, a sofa of 84 x 36 x 34, a dresser of 60 x 18 x 36, two bookcases of 36 x 12 x 72 and twenty boxes of 18 x 18 x 16 add up to 208.6 cubic feet.
At 8 feet of height and a 75% fill, that needs 208.6 / 0.75 / 8 = 34.8 square feet of floor. The smallest listed size with at least that much floor is 5 x 10 feet, which has 50 square feet. A 5 x 5 unit has 25 square feet and is too small.
Why volume rather than footprint
Items are stored in three dimensions. Boxes stack, sofas can stand on end and mattresses can lean on a wall. Using volume and a usable height treats the unit as a space to fill up to the ceiling, then converts it to floor area, which is how unit sizes are named.
The fill share is the biggest judgment in the estimate. A tidy load of uniform boxes can fill 80% or more. A load of furniture with awkward shapes may fill much less. If you will need to reach items at the back, lower the share to leave a walkway.
Choosing with some room to spare
The table shows which sizes fit and how much space is left over. If your result sits just under a size, consider whether you might add things later. For help counting boxes before you start, see the moving boxes calculator, and for the cost of the move itself, the moving cost calculator.
Facilities offer different sizes, door openings and ceiling heights, and the sizes listed here are examples. Check measurements with the one you will rent. Heavy items should not be stacked high, and stacking is only safe for things made to be stacked.
Assumptions and limits
- Sizes are in inches for items and feet for units. Units are listed as width by depth in feet.
- The listed unit sizes are common examples. Your facility may offer others.
- Items are treated as solid blocks of their outer dimensions. Hollow space, such as inside a chair, is not credited.
- The share you can fill is your own assumption, and a lower share gives a larger unit.
Frequently asked questions
What size storage unit do I need for a one bedroom apartment?
It depends on what you own. Enter your items to see. The example load of a bed, sofa, dresser, two bookcases and twenty boxes needs about 35 square feet of floor, so a 5 x 10 unit.
What if my total needs more than the largest size?
The tool shows how many of the largest listed unit you would need. You can also ask the facility about larger units or a different layout.
Does the tool assume everything can be stacked?
It assumes you can use the whole height of the unit at the fill share you set. For items that cannot be stacked, such as a fragile sofa, lower the fill share.
How do I measure an item?
Use the longest length, widest width and tallest height, in inches, as if the item were in a box. Round up if unsure.