Buying costs less than renting in all 100 large U.S. metros, according to the Rent vs. Buy Report from Trulia (TRLA). Low mortgage rates have kept homeownership from becoming more expensive than renting. In some markets, rents have risen sharply; rising rents hurt affordability relative to incomes, but rising rents make buying look cheaper in comparison. To compare the costs of owning and renting, Trulia’s model assumes buyers get a 4.5% mortgage rate on a 30-year FRM with 20% down payment. Further, it assumes buyers itemize their federal tax deductions and are in the 25% tax bracket; and will stay in their home for seven years. Under these assumptions, buying is 38% cheaper than renting nationwide, taking into account all of the costs and proceeds from buying or renting over the entire seven-year period.