His female colleague, however, will not only need more in savings to tide her over in retirement—$1,717,779, thanks to projected higher health care costs and a likely longer lifespan—but will only have set aside that same $992,648 by the time she turns 65.

Related: Solution to gender pay gap remains elusive

And that’s without a career break.

If she steps out of the workforce between ages 35–45, she’ll need to save $1,927,424 to make up for it—but instead she’s likely to have a nest egg of just $619,945 by the age of 65. That’s a shortfall of $1,307,479, considering wage inflation and time out of the workplace.

A break between ages 45–55 would necessitate saving $1,870,248, and for a break between ages 55–65 she would need to save $1,813,072.

But neither of those totals is any more likely to be achieved; instead, the female worker with a gap between ages 45–55 will only save $759,267, resulting in a gap of $1,110,981, and the female worker with a gap between ages 55–65 will save $857,185, resulting in a gap of $995,887.

So if millennial women aren’t going to come up short at retirement, how much do they need to save throughout their careers?

Those who take an early career gap should plan on putting away 25 percent of their pay as long as they’re working, while the two later age groups should stick with 19.2 percent and 16 percent, respectively.

Young women who don’t take time out for family or caregiving responsibilities should be saving 12.6 percent—no easy task in the face of lower-paying jobs and student loans.