How do you know if you should refinance your mortgage? Here's a good rule of thumb:

Do it if you can lower your mortgage rate by a percentage point or more.

Reduce your interest rate by one percentage point and you'll reduce your monthly payments by $65 a month for every $100,000 you borrow.

Our extensive database of mortgage rates from scores of lenders is a quick way to check and see if rates are low enough.

The only other thing to consider is how much you'll have to pay in fees and closing costs.

Ideally, you should save enough with your new payments to recoup all of your up-front costs in less than a year.

Two years or more is too long and indicates that you're paying too much for the interest rate you're being offered.

Interest.com's refinancing calculator can help you evaluate any offer.

It will figure out exactly what your new payments will be and how long it will take to pay for the fees and closing costs.