10x30 storage unit cost: the largest standard size

A 10x30 is 300 square feet, at 8 feet of ceiling indoors and often 10 to 12 in a drive-up, so somewhere between 2,400 and 3,600 cubic feet. It sits at the flattest end of the price-per-square-foot curve. The curve is steep at the small sizes, where a unit's fixed costs (its door, lock, light, aisle frontage and share of the security and administration bill) are spread over very little floor, and it flattens out by the time you reach a few hundred square feet. There is nothing larger to step up to at most operators, because anything bigger is usually let as commercial space on different terms.

So the ordinary logic of sizing up stops applying here, and something else takes over: supply. Most facilities build a unit mix weighted to the sizes people rent most, which are the small and mid ones, and hold only a handful of 10x30s. A site with one left does not discount it, and often will not put a promotion on the size at all. In markets with strong vehicle-storage or commercial demand, those few units are also competing with renters who have nowhere smaller to go. This is why two facilities a few miles apart can quote very differently for the same 300 square feet on the same day, and why a national city table for this size was misleading even when it looked authoritative.

The one rent figure here you can check for free comes from an annual report rather than a listing page. Public Storage's Form 10-K, FY2025 (filed 12 February 2026, period ending 31 December 2025) reports realized annual rent of $22.54 per occupied square foot across its Same Store Facilities, against $22.43 a year earlier, at 92.0% average occupancy. Do not multiply it by 300. It blends every unit size and market the company operates in, and the largest units sit well below that blend, so the arithmetic overstates a 10x30 by a margin public data cannot pin down.

This page used to run a worked example here with specific monthly rates in it. Those rates were invented, so the arithmetic has gone. The argument underneath it was sound and does not need them.

Structurally, one large unit should win. A unit's fixed costs land once per unit and do not scale with its floor, so two units make you pay that load twice: two administration charges, two locks, two lots of cover, two agreements. What works the other way is promotion. Facilities discount the sizes they hold a lot of and need to keep full, which are the small and mid ones, and they rarely discount the largest size, of which they hold few. When a site is running hard on 10x10s and 10x15s and has one 10x30 left at asking price, the pair can come out level or ahead. That is a fact about that site in that month, not a general rule, which is why the honest instruction is to get all of it quoted rather than to read a table.

Where the split genuinely earns its keep is function rather than price. Two units let you put a vehicle or garden equipment in a drive-up and the sensitive half of the load in an indoor climate unit, which one 10x30 cannot do. They let two family members or business partners each hold their own key. And they let you give one up later without unpicking the whole arrangement. If any of that describes your situation, price the split even if the single unit is slightly cheaper.

The check is simple. Ring the site and ask for three numbers on the same call, all quoted as the month-two rate: one 10x30, two 10x15s, and whichever climate option you would actually want. Ask what promotions apply to each. Then compare, including the duplicated administration charge and cover on the pair.