So what rate would you need before refinancing makes sense? That's what this worksheet is designed to tell you. One thing to keep in mind, though: The interest rate isn't the only thing to consider when shopping for a new loan. Refinancing, after all, isn't free. There are the bank fees, the bills for a new appraisal and inspection, your lawyer's fee — you name it. This worksheet will help you figure out how much you'll save on your monthly payments with a lower rate and how long it will take, given those savings, to repay the cost of getting a new loan.

To figure out which is best, you've got to consider both your best and your worst-case scenarios. Our worksheet can help. Just fill in your numbers and then use the graph and "compare" feature to evaluate your fixed and adjustable options based on the total amount of interest paid as well as the amounts of your first and last payments.

Mortgage points can refer to loan origination fees (fees charged by the underwriter) or discount points (also known as loan discounts). The worksheet focuses on discount points, which represent 1% of the total loan amount. By paying a discount point, you can lower your interest rate. Consider it prepaid interest.

This calculator will "score" your credit using the number of late payments you have on various credit accounts. This isn't a true "credit score," but will give you a pretty good idea of how you'd fare. Please note that different lenders may count late payments older than 12 months against you; ours doesn't. And different lenders may assign you a higher or lower score, depending on their internal underwriting requirements.