It depends. Normally it is between 7-8 years. Yes, paying mortgage interest sucks because mortgage interest is "front loaded". That means that for the first 3-5 years of your mortgage you pay 85-90% towards interest on a 30 year mortgage depending on a few factors. IF you can, than I suggest paying extra towards the principal and that will help you pay the home earlier and pay way less in interest. The shorter the term of the mortgage, the lesser you pay in interest. Normally on a $150K 30 year loan @ 4.5% interest you will pay $146K in finance charge, and that means that you paid $296K for that house at the end of that 30 year term.