By contrast, 1.1 million men were at-home dads in 1989, the earliest year reliable government figures are available for the sector.
Gretchen Livingston, a senior researcher who worked on the report, said fathers comprised 16 percent of parents at home full time in 2012, up from 10 percent in 1989.
The 21 percent who cited caring for home and children as the specific reason for being out of the for-pay work force was up from 5 percent in 1989 and 18 percent in 2007, the start of the recession, Livingston said.
While unemployment is a factor overall, Livingston said Wednesday in a telephone interview from Washington, D.C., that the "continuing convergence of gender roles" between moms and dads is key.
"It's becoming more acceptable for dads to be caregivers, and it's becoming more acceptable for moms to be responsible for breadwinning," she said.
But Livingston warned that affluent, highly educated dads at home to raise children remain a subset.
"It's important to note that a lot of these dads are actually not doing that well economically and they tend to have lower income levels, too," she said.
And despite a greater acceptance of dads staying home to raise kids, other Pew research shows 51 percent of the public believes kids are better off when the mother stays home, compared to 8 percent that cited dads.
"There clearly has been a lot of gender convergence in recent decades, but then at the same time, you know, some things haven't changed as far as people's perceptions of the roles," Livingston said.
Mike Brandfon, 48, of Chicago falls into the laid-off category. He lost his job at a mid-size public relations company in December 2009, at a period when he and his wife had been thinking about having kids.
"I was looking for jobs but we just happened to get pregnant with twins at the right time, as far as me being able to stay home with them since I couldn't find a job," he said.
After the girls were born in October 2010 and his spouse's four-month maternity leave ended, her marketing job allowed them to just make ends meet.
"It was quite a shock, to say the least," he said of remaining out of the for-pay work force. "You don't think about it in that sense when you're going through it. You just try to get through each day and each moment."
Brandfon joined a dads' group for park outings with the kids and the occasional night out for a beer. Once the girls were nearly 3 years old, he began looking for work again and landed a job last September as media director for Web2carz.com, an online-only auto and lifestyles magazine.
In the end, he was thrilled with his time home as primary caregiver.