30 percent of working-age adults—aged 23 to 65—live in doubled-up households, up from a low of 21 percent in 2005 and 23 percent in 1990.

Adults living with roommates or family members earn 67 cents for every dollar made by adults who live on their own (or with a partner).

More than half (54 percent) of young adults aged 23-29 live in doubled-up households, with either roommates or family members.

As rent consumes a growing share of household income in many cities, some people must relocate or find ways to offset rising prices. An increasingly popular way to cut costs is by adding a roommate. Nationally, 30 percent of working-age adults—aged 23 to 65—live in doubled-up households, up from a low of 21 percent in 2005 and 23 percent in 1990.[1]

We define a doubled-up household as one in which at least two working-age, unmarried or un-partnered adults live together. For example, a 25-year-old son living with his middle-aged parents would constitute a doubled-up household, as would two 23-year-old roommates who are not partnered to each other. A doubled-up household contains people who might choose to live apart under different circumstances, financial or otherwise.

Some people do choose to live with others for companionship or convenience. However, our research suggests that the trend toward doubling-up is often driven by financial concerns. For instance, there is a strong relationship between doubling-up and rental affordability: In metro areas where rent drains a larger share of household income, more adults choose to live with roommates or family members. Some of the most extreme examples include Los Angeles (46 percent doubled-up), Miami (41 percent), and San Francisco (38 percent).

There is other evidence that doubling up is motivated by affordability concerns. The median individual income of an employed adult in a doubled-up household is $30,000, compared to the $45,000 earned by their non-doubled-up counterpart. In other words, adults living with roommates or family members earn 67 cents for every dollar made by adults who live on their own (or with a partner). This suggests that in many places, employed people who currently live in doubled-up households would not be able to afford rent if they lived by themselves.

Since 2005, the share of adults doubling up has increased year-over-year in every age bracket. But the share of twenty-somethings (aged 23 to 29) living in doubled-up households has climbed faster than any other age bracket, from 39 percent to 54 percent in just 11 years.

At first glance, this trend might be attributed to more unemployed young people living at home with their parents. However, the likelihood of doubling up has increased at the same rate among employed and unemployed adults since 2005, regardless of age. A more likely hypothesis is that young people are especially likely to be underemployed: Despite high education levels, many twenty-somethings work in relatively low-wage jobs, rendering some of them unable to afford escalating rents on their own.

When working-age adults are doubled up, it’s typically because they live with either roommates or family members. While the share of working-age adults in both situations has risen since 2000, the rate of family members doubling-up has risen more dramatically. As of 2016, 73 percent of doubled-up adults live with family members rather than roommates, up from 70 percent in 2000.

[1] Based on a Zillow analysis of individual Census responses in the Integrated Public Use Microdata Series: Version 7.0.