A 4×5 storage unit: what it is, what fits, what it costs.
There is no standard 4×5 storage unit. A 4×5 is 20 square feet (about 160 cubic feet at an 8 ft ceiling), which sits between locker size and the smallest distinct unit operators rent, the 5×5 (25 sqft, ~200 cubic feet). Search for a 4×5 and you are booked into a 5×5 in almost every market — five extra square feet at the 5×5 price. A genuine 4×5 exists only as a locker, at the minority of facilities that rent lockers (Extra Space lists lockers up to 4×5 and 5×5).
Because you end up in a 5×5, budget the 5×5 rate: roughly $45/mo nationally in 2026, from about $29/mo in Fort Worth to $167/mo climate-controlled in Boston.
How a 4×5 compares to what you can actually rent.
Cubic feet = floor sqft × 8 ft ceiling. Standard sizes are distinct units Public Storage rents; a 4×5 rounds to the 5×5 unless a facility rents lockers.
Why operators skip from a locker to a 5×5.
Self-storage is built on a small number of standard footprints — 5×5, 5×10, 10×10, 10×15, 10×20 — so a facility can lay out a building efficiently and quote a rate instantly. A 4×5 falls in the gap between a locker (roughly 10 square feet) and the 5×5, and the extra five square feet a 5×5 gives costs the operator almost nothing to build. So rather than stock a 4×5, operators rent you the 5×5. Where a location does carry lockers, a 4×5 or 5×5 locker is the genuinely smaller option, but those are the exception rather than the rule.
The practical upshot: do not spend time hunting for a 4×5. Price and book a 5×5. It is the smallest thing most facilities rent, it costs the same as a 4×5 would, and you get a little more room. See what actually fits in the 25 square feet before you book.
Is there a 4x5 storage unit?
Not as a standard walk-in unit. Public Storage and the other major operators do not rent a 4x5; their smallest distinct unit is the 5x5 at 25 square feet. A 4x5 is 20 square feet, which falls between locker size and the 5x5, so a search for a 4x5 unit is served by a 5x5 in almost every market. Some facilities that rent lockers list a 4x5 locker (Extra Space lists lockers up to 4x5 and 5x5), so a true 4x5 exists as a locker in a minority of locations.
How big is a 4x5 storage unit?
A 4x5 has a 4 ft by 5 ft floor, so 20 square feet, and about 160 cubic feet at the standard 8 ft ceiling. That is one fifth smaller than a 5x5 (25 sqft, 200 cubic feet) and roughly the footprint of a small walk-in closet.
What fits in a 4x5 storage unit?
About a closet's worth: a few moving boxes, a couple of suitcases, and a small piece of furniture like a chair or nightstand. Because you will almost always be renting a 5x5 instead, you get slightly more room in practice: 5-8 boxes plus small furniture and seasonal items per Public Storage guidance.
How much does a 4x5 storage unit cost?
Since a 4x5 search lands you on a 5x5 in nearly every market, expect the 5x5 rate: about $45/mo nationally in 2026 (a triangulated estimate, since no operator publishes a single national figure). Across the 18 US metros tracked on this site, promo-stripped rolling rates run from roughly $29/mo in Fort Worth to $167/mo climate-controlled in Boston. A 4x5 locker, where one exists, is usually the same price band or a little less.
What is the difference between a 4x5 and a 5x5 storage unit?
A 5x5 has 25 square feet of floor; a 4x5 has 20. The 5x5 is the one operators actually stock and rent, so in practice the difference is academic: booking a 4x5 gets you a 5x5, five extra square feet, at the 5x5 price. Only if a facility rents lockers will you get an actual 4x5.
Is a 4 by 5 storage unit the same as a 4x5?
Yes. 4 by 5, 4 x 5 and 4x5 all mean a 4 ft by 5 ft footprint, 20 square feet. None of those spellings is a standard operator unit; each rounds to a 5x5 unless the facility rents lockers.