Rising interest rates might be great news for your savings accounts, but they're not such great news for anyone whose mortgage rates adjust with the rising tide. In fact, adjustable-rate mortgages appear to be putting a financial strain on some homeowners.

The Mortgage Bankers Association's survey of nearly 43 million loans found that late payments jumped in the third quarter this year. The late payment rate was significantly worse for borrowers who carry subprime mortgages, loans offered at higher rates to home buyers who may have a few credit flaws.

Borrowers with subprime, adjustable-rate mortgages fared the worst. The Associated Press reported their delinquency rate exceeded 13%. Adjustable-rate mortgages are starting to squeeze some budgets.

At the same time, Bankrate (NASDAQ:RATE) reports that mortgage rates have recently fallen to new lows. You may be wondering whether now's the time to refinance your adjustable-rate mortgage into something more stable before the next rate hike comes along.

Figuring out whether to refinance your mortgage can be emotionally and logistically easier than buying a house. There's no need to travel all over the city and get your heart set on the perfect dream home, only to see it snatched up by someone else.

Refinancing is an economic calculation, but it does have a lot of variables. The big question to ask is whether you'll save more by reducing mortgage payments than you'll spend by refinancing.

That calculation will depend on a host of factors, such as the size of the rate cut, the length of time you've been paying your mortgage, and the size of your closing costs. On that last point, you'll have to do some homework. Make sure to ask for estimates of your closing costs when shopping around for a new loan. You'll want to use the information while calculating whether it's a financially good decision to refinance your loan.

Another cost you'll want to consider is any penalty levied by your current mortgage for prepaying the loan. That may offset any savings you gain by converting your mortgage to a lower rate, making all this work basically useless.

When trying to figure out whether refinancing can pay big dividends, take advantage of the marvels of the modern world. The easiest way to make this calculation is to find an online calculator, like the one right here at The Motley Fool. It will ask you to insert information about your current loan and your new loan, including its costs. After you've filled in all the blanks, it will tell you how much you'll save over the time you expect to be in the house.

You can use this calculator in two ways. First, compare your current mortgage to a hypothetical refinancing loan if you're thinking about starting to shop around. It may tell you instantly whether or not it's worth your time to pursue this project. (After all, wouldn't we rather spend our time at the kids' soccer games or watching classic movies on cable television?)

Second, if you decide to refinance, the calculator will help you compare offers from different lenders. With different cost structures, it can be hard to compare different loans. Plug in the information from each and see which saves the most.

If you hold an adjustable rate mortgage and you're thinking about switching to a more predictable fixed-rate loan, think back to the reasons why you took the original loan in the first place. If you simply wanted the lowest rate you could find, and you found that in an adjustable-rate mortgage, it may be time for you to refinance the loan. If, however, you plan to move out of the house before your rate can rise too far, you may be in the right place for your situation.

Before the fear of rising rates causes you to rush out the door and into the arms of the first lender you meet, take a close look at the terms of your adjustable-rate mortgage. Look at the index that your rate is tied to. Find out when and how often your loan adjusts. Look for annual and lifetime caps. Look, too, at the initial adjustment cap. You may fear a bigger rate hike than you're actually facing.

Find out more about home loans in the Home Center. Another resource, Motley Fool GreenLight, offers a lot of detailed information about the variables involved in refinancing. And unlike your mortgage, it's free for 30 days.

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Bankrate is an Income Investor selection.

Fool contributor Mary Dalrymple welcomes your feedback.