Gary Jonas, former president of the Building Industry Association of Philadelphia, said that stat is largely what’s driving the dip in average apartment size. But he doesn’t view the change as an outright negative.

“Maybe a generation ago, two people would get an apartment as roommates and rent together, and then you would get a two-bedroom apartment. Now what you’re seeing is people wanting to live alone and that forces them, because of what they can afford, into a studio,” said Jonas, managing member of the HOW Group, a real estate company that serves Greater Philadelphia.

They’re also willing to live in a smaller space if the building offers certain amenities.

“Now every building that gets built in the city has a gym, a rooftop deck and co-working space. So people are trading some of the apartment space for space outside the apartment and experience. So it’s a nuanced scheme. There’s a lot of things going on here,” Jonas said.

At the same time, studios are valuable for developers because the price per square foot is higher than it would be for a larger place.

The report comes as Philadelphia’s housing market remains tight, sidelining would-be homeowners who are remaining renters for longer. And while studio and one-bedroom apartments have gotten smaller, three-bedrooms are larger than the national average.