Dozens of sites offer rent-versus-own tools or calculators that use different variables in their models (some quite detailed), allowing you to enter comparative data into each field and quickly see the effect of changing the amount of rent or the price of a house so you may decide whether to rent or own. Some calculators may consider such factors as rapid increases or decreases in home prices over the years, current mortgage interest rates, and changes to tax codes. Investigate the currency of the data each calculator uses.