Traditionally, the decision on whether or not to refinance has meant balancing the savings of a lower monthly payment against the costs of refinancing. But in recent years, companies have introduced "no cost" and low cost refinancing packages that minimize or completely eliminate the out-of-pocket expenses of refinancing. (These refinancing packages compensate with a higher interest rate, or by including some of the costs in the amount that is financed.)
With traditional refinancing, the most often cited rule of thumb is that the interest rate for your new mortgage must be about 2 percentage points below the rate of your current mortgage for refinancing to make sense. However, with the newer low and no cost refinancing programs, it can be worth your while to refinance to obtain a smaller reduction in interest rates.
How long you expect to stay in your home is also a factor to consider. If you'll be moving in a few years, the month to month savings may never add up to the costs that are involved in a refinancing.