One of the most confusing mortgage choices is whether to pay points. It doesn’t help that the term is used two different ways, or that the right answer varies by situation. But the good news is that you can boil your decision down with a simple math calculation.

A “point” refers to one percent of your loan amount. So on a $200,000 mortgage, one point equals $2,000. You also need to be aware that lenders quote two kinds of points. Origination points are a fee you pay the lender for their services, and you may or may not be able to negotiate it.

But discount points are different, and are the ones borrowers find themselves dithering over. A discount point is a pre-payment of interest at the time of closing in exchange for a lower mortgage interest rate. It allows you to “buy down your rate”.

Lenders often let you pay one to three points, but we’ll use an easy one-point example. Opting to pay a point at closing typically lowers your mortgage APR by about a quarter percent (though lenders vary). So for a $200,000 mortgage with a 30-year fixed rate of 3.75 percent, paying one point, or $2,000, could lower your rate to 3.50 percent, which would drop your monthly payment from $926 to $898.

Now divide the cost of the point ($2,000) by the monthly savings ($28) to see how long it will take to break even. In our example, it would take 72 months, or six years, to earn back your $2,000 investment. Expect to stay in your home longer than that? Then buying points makes good sense.

Of course, if you can’t afford to bring more money to closing, or you have a higher-priority use for your funds, a no-point mortgage will be your own smart mortgage choice.