If you saw the map we shared last month of the minimum earnings required to live in each state, you already know it takes a fairly substantial income just to get by. Living comfortably is an entirely different story. Financial services website GOBankingRates.com recently conducted a cost-of-living survey for the 75 most populous cities in America, comparing the salary it would take to live comfortably with the actual median income.

GOBankingRates.com calculated their estimations based on the 50-30-20 rule of budgeting. The guideline states that 50 percent of what you make should cover all essentials like food, shelter, transportation, and utilities. Of the remaining 50 percent, 20 percent should be set aside for savings and debt payments with the other 30 percent going towards lifestyle expenses like movies, vacations, gym memberships, and meals out.

Let's get down to it: According to PayScale, which analyzed GOBankingRate.com's numbers, the five most expensive cities in the U.S., are San Francisco, San Jose, New York, Boston, and Washington, D.C.

San Francisco was the most costly city by far, with an estimated income of $119,570 required to afford a comfortable lifestyle. In reality, the median salary earned by San Francisco residents is $78,378, and while that may be enough to cover rent and other necessities, it doesn't leave much for savings or entertainment costs.

Nearby San Jose claimed the number two spot, with a salary of $89,734 needed to live there comfortably. Three major East Coast cities rounded out the rest of the list, with an income of $87,446 needed to live well within your means in New York City, $84,422 for Boston, and $83,104 for residents of Washington, D.C.

For many professionals, especially those just starting out, the 50-30-20 rule is a goal to strive towards. Still, it never hurts to know how far your dollar will get you in your area the next time you're negotiating salary expectations.