In six states and Washington, DC, families that want to rent a two-bedroom apartment without spending an unreasonable amount on housing will need to make more than the median household income in the US.

The general rule of thumb is that no more than 30 percent of your income should go to rent. But the latest report from the National Low Income House Coalition makes clear that for many families, that's not really possible. In Hawaii, the most expensive state, a household would need to earn more than $71,000 per year in order to afford a two-bedroom apartment without going over the 30 percent threshold:

The report uses the "fair market rent," or rents at the 40th percentile in a given housing market. That means 60 percent of apartments are even more expensive. (Whether you're in an urban area or not can matter as much as, or more than, what state you're in. The group's website has an excellent interactive feature that lets you explore states in more detail.)

Nationally, the report concludes, the housing wage — the amount that a worker would need to make working full time in order to afford a one-bedroom apartment comfortably — is $16.35.

The report also picks out the 10 metropolitan areas where you need to earn the most in order to afford a two-bedroom apartment comfortably. In San Francisco, that translates into a nearly six-figure salary.

Watch: 120 years of population shifts in one map