Take, for instance, a couple who buy a $500,000 home and make a down payment of 20 percent, or $100,000. With a 6.43 percent interest rate on a 30-year fixed loan, their monthly payment would be $2,510. Over the 30-year life of the mortgage, they would pay a total of about $1 million for the home, including the down payment.

But what if that couple had waited and the home price dropped 9 percent to $455,000 but mortgage rates rose to 7.01 percent? Now, the 20 percent down payment would be $91,000, and the monthly payments $2,424. The buyers would end up paying a total of about $964,000 for the house, or nearly 4 percent less. If the buyers were able to refinance to a lower rate a few years later, the total cost could be even lower.

The calculations change, however, when mortgage rates go even higher. Once the rates move above 7.36 percent, they begin to lose the benefits of the 9 percent drop in the house price.

If you are looking for an apartment in Manhattan, where prices are near their highs and are not expected to fall as much has they have elsewhere, the rise in mortgage rates quickly starts to affect how much you can afford. A $500,000 apartment (which could be a studio, since this is Manhattan we’re talking about) with a $100,000 down payment at a 7.01 percent rate means your monthly payments would be nearly $2,664. The total cost of the property, including down payment, would be $1.06 million.

“Prices have come down quite a bit since the top of the market, and home values are better than they were a year ago,” Ms. Chen said. “But I am still cautioning to wait and see how much further prices will fall, particularly in regions that were most overblown during the housing boom. If you’re looking for bargain basement prices, I don’t think we’re there yet.”

Mortgage rates, on the other hand, may be even less predictable. For all we know, “they might go down next week or the week after,” she added. “In the longer term, rates are still relatively attractive to where we think they might be next year.”

That is why it may be wise for homeowners looking to refinance out of, say, an adjustable-rate mortgage, to lock in a rate now. If your house drops in value, and rates continue to balloon, you may be out of luck.