When you are evaluating whether to buy or to rent, you should consider a few important variables. According to real estate editors at The New York Times, you should consider how much and how fast real estate purchase prices and rental prices are increasing or decreasing, and for how long you plan to stay in the house. According to The New York Times rent calculator, assuming such factors as your income and deductions available to purchase a house (such as deduction of mortgage loan interest), a nominal 2% annual house price increases, and nominal 3% annual rent increases, if you plan to stay in the house for five years or longer, you should make the investment and purchase the house. If you decrease the time to four years or less, you should rent.