Homeowners have been on a refinancing binge in the past year, scrambling to get out of their adjustable rate mortgages and into fixed rate mortgage, or FRMs. Refinancing accounts for 43% of mortgage activity, while only 2.5% of new applications are for ARMs, according to the most recent Mortgage Bankers Association survey. But refinancing isn't always the right move. Here's why: Many homeowners refinance to take advantage of a lower rate or avoid an anticipated interest rate hike on their ARM. But refinancing can be costly. Closing costs average 2% to 4% of the loan amount, and it can take a while for the savings from lower monthly payments to pay back the upfront costs of refinancing. If you sell the house before you've had the chance to recoup those costs, refinancing was a bad idea. So how do you calculate the break-even point where the savings from a refinancing outweigh its costs? If you are refinancing from one FRM to another because of lower rates, you can crunch the numbers with the help of the online Refinance Interest Savings calculator at BankingMyWay.com. Enter the details of your current loan and your new mortgage, and the calculator will tell you how much lower your monthly payments will be and when you stand to break even. Say you have 15 years left on a $200,000 mortgage at 8.5% on a home originally worth $250,000. You want to refinance to take advantage of the current lower rate of 6.22% on a new 15-year mortgage that covers the remaining balance of your original loan. Your closing costs total $3,000. According to the calculator, you would save a little more than $200 in monthly payments, and you'll break even after 15 months.