Companies such as EasyRoommate offer online listings for single rooms for rent, categorized by location. SpareRoom.com is another website with similar listings, but as of 2015, it's limited to New York. People wanting roommates of the same culture have access to such sites as Indian Roommates.
Visit a website offering single rooms for rent, and enter the location by state and metropolitan area. To narrow down the results, enter your minimum and maximum rent that you want to pay each month, and whether you want to live in a house or apartment. Indicate if you have a preference about the total number of bedrooms in the home, and choose whether the ad poster accepts short-term arrangements, provides furniture and has posted images about the home, notes EasyRoommate.
Some sites, such as SpareRoom.com, allow you to enter the minimum and maximum age of others already living in the unit and whether you would prefer a student or a professional as your roommate. After you've entered those parameters, the website narrows down the choices even further. Click on the link for any properties that match your interest.
Online classified ad listing services such as Craigslist also offer rooms for rent among their listings. Craigslist has a general location page for each major metropolitan area, with a specific link for rooms for rent. The search results page offers a series of links, each corresponding to a room available for rent.