Average U.S. apartment sizes have risen but not in San Diego where space is at a premium.

San Diego’s average new apartment size was 827 square feet in 2025, said a new study from rental website RentCafe, less than the national average of 910 square feet. San Diego’s apartment size was unchanged from the previous year, whereas the national average increased by 13 square feet annually.

RentCafe said a burst of apartment construction across the nation for several years has meant developers are in heavy competition for tenants — and one way they are trying get them is by offering bigger units.

Another factor: Land is less expensive in the South than in coastal cities where many people have moved, RentCafe said, so it is easier for developers to build big and cause the overall average to rise.

Tallahassee, Fla., had the biggest average size in new apartments in the nation at 1,156 square feet. It was followed by Gainesville, Fla., at 1,126 square feet, and Baton Rouge, La., at 1,042 square feet.

San Diego does not have the smallest apartments in the nation or the state, and they are practically huge compared to other cities.

Seattle had the smallest new apartments in the U.S. at an average of 645 square feet. It was followed by Portland, Ore., at 665 square feet, and Tacoma, Wash., at 684 square feet.

Out of 100 cities, San Diego ranked No. 72 in average new apartment size, behind only Fresno (980 square feet) and Irvine (950 square feet) in California. The smallest new apartments in the state were in San Francisco, at 717 square feet; Oakland, at 739 square feet; and Los Angeles, at 770 square feet.

The RentCafe study looked at city data (not county or metro area) from research firm Yardi Matrix. On the county level, the region has a legacy of building larger apartments, but that has been changing.

In 2015, The San Diego Union-Tribune studied average apartment sizes and found they were getting bigger. At the time, one of the reasons given was that, coming out of the Great Recession, it was still difficult for potential homeowners to afford buying a place, so they needed to continue renting. Developers responded by increasing the number of two-bedroom units.

Looking ahead at new construction, it appears San Diego County is going full steam ahead on smaller apartment sizes, said the database of real estate tracker CoStar. Out of 21 projects now under construction (with publicly available unit sizes), only five apartment complexes have units over the 827-square-foot average. The average apartment size of all the projects is 704 square feet.

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