According to Freddie Mac, the average interest rate on a 15-year mortgage is 3.36% — a record low. That means if you refinance a 30-year fixed mortgage with a balance of $250,000 into a 15-year fixed loan, your monthly payment would go up less than $300, and you would save a whopping $220,000 in interest over the life of your loan — not to mention have your home paid off in half the time. (Note: This math doesn’t account for any refi costs, which can run anywhere from 1% to 3% of the loan amount.) One end run around origination fees and other costs of refinancing is to ask your lender for a quote on a low or no-cost refi.