A lender hands you two options on a $400,000 mortgage. Option A: 6.5% with no points. Option B: 6.0% with two discount points. The second one sounds like a bargain until you notice those two points cost $8,000 out of pocket at closing. So which loan actually costs you less?
That is the entire job of a discount points calculator. It takes three numbers — the cost of the points, the monthly payment at each rate, and how long you expect to keep the loan — and spits out a breakeven point in months. Miss that breakeven by a year or two and you have handed the lender thousands of dollars for nothing.
What Discount Points Actually Are
One discount point equals 1% of your loan amount. On a $400,000 mortgage, one point is $4,000, paid at closing. In return, the lender permanently lowers your interest rate.
How much lower? Usually about a quarter of a percentage point per point, though it moves around. Lenders have quoted anywhere from 0.125% to 0.5% per point depending on loan type, credit score, and whatever the bond market did that morning. Two points at a quarter point each gets you roughly half a percent off.
Discount points vs. origination points
These two get mixed up constantly, and the confusion costs people money. Origination points pay the lender for writing the loan — they buy you nothing in terms of rate. Discount points buy down the rate itself. Both show up on your Loan Estimate, both are calculated as a percentage of the loan, and only one of them changes your monthly payment. Read the line items carefully before you agree to anything.
How the Calculator Crunches the Numbers
The math is refreshingly simple. You need:
- The total cost of the points in dollars
- Your monthly principal and interest with the points
- Your monthly principal and interest without them
Subtract the two payments to get your monthly savings. Divide the points cost by that savings. The result is the number of months it takes to break even. After that point, every payment is money in your pocket.
A $400,000 worked example
Stick with the scenario from the top. At 6.5% on a 30-year fixed loan, principal and interest run about $2,528 a month. At 6.0%, they drop to roughly $2,398. That is $130 back in your pocket every month.
Two points cost $8,000. Divide that by $130 and you get about 61.5 months — a hair over five years. Sell, refinance, or pay the loan off before that five-year mark, and the points were a losing bet. Stay for ten years and you pocket roughly $7,600 in savings. Stay the full 30 and the rate reduction is worth about $46,800 in avoided interest, minus the $8,000 you paid up front.
Breakeven Is a Starting Point, Not a Verdict
A quick breakeven number is tempting to treat as the final answer. It isn’t. Three things typically blow up the tidy calculation.
How long you’ll actually stay. The average homeowner moves or refinances well before 30 years. If your career, your family, or your plans might pull you out in four years, a 62-month breakeven is a bad trade regardless of what the calculator says. Be honest about the timeline, not optimistic.
What the loan costs after the points. A lower monthly payment is only half the picture. Run the loan long enough and the total interest calculator shows the number your monthly payment hides — and that figure is where points really earn their keep over a long holding period.
Whether the cash could work harder elsewhere. More on that below, because it is the argument most borrowers never hear.
The Cash You Spend Has an Opportunity Cost
That $8,000 does not exist in a vacuum. If instead of buying points you invested it and earned a 7% annual return, it would grow to roughly $11,200 in five years. Meanwhile, five years of $130 monthly savings gets you to about $7,800. On a pure five-year horizon, the investment wins.
That is not a case against points. It is a case for measuring both sides properly. If you want a straightforward way to compare returns on money you’d otherwise park somewhere, the ROI calculator for measuring returns without guessing handles that comparison in a couple of minutes. Higher-rate environments shift the answer; right now, the spread matters.
Don’t Ignore the Tax Angle
Discount points on a purchase mortgage are often deductible as prepaid interest in the year you pay them, provided you itemize and the loan is secured by your main home. On a refinance the rules tighten — the deduction is generally spread across the loan’s life instead. On $8,000 of points in the 24% bracket, that could be close to $1,900 shaved off your tax bill.
Whether it helps you depends on whether you take the standard deduction at all. The guide to what your mortgage interest is really worth at tax time walks through the itemizing math so you aren’t counting on a deduction you can’t actually claim.
When Points Make Sense — and When They Don’t
Rules of thumb are blunt instruments, but these hold up well:
- Points tend to work if you’re buying a forever home, putting down roots for a decade or more, and you have cash left over after closing for an emergency fund.
- Points tend to fail if your breakeven sits past your realistic holding period, if you’re stretching to afford closing costs already, or if you’d be draining savings to pay for them.
- Points are a coin flip on refinances, where the clock resets and you’re already paying closing costs all over again.
The worst version is paying points with borrowed money or with funds that were earmarked for repairs and moving costs. A slightly higher rate you can comfortably afford beats a lower rate that leaves you broke the week you move in.
Temporary Buy-Downs Work Differently
Not every rate reduction is permanent. A 2-1 buydown, sometimes funded by the seller, drops your rate by 2% in year one, 1% in year two, then returns to the note rate in year three. Your payment rises each year on a schedule, and the savings are front-loaded into the months right after closing — which is exactly when cash is tightest.
Comparing a temporary buydown against permanent points is not an apples-to-apples calculation. The buy-down points calculator for figuring out when points pay for themselves handles the permanent side; for buydowns you want to model each year’s payment separately before deciding.
Comparing Two Offers Without Getting Fooled
Lenders compete on presentation as much as price. One quotes a low rate with high fees, another quotes a higher rate with a lender credit. The advertised rates tell you almost nothing.
Line up the Loan Estimates side by side and run both through the same calculator with identical assumptions: same down payment, same term, same holding period. The tool for comparing interest rates across two loans does this cleanly, and if you want the full picture including closing costs, taxes, and insurance, the scenario comparison calculator showing the true cost of a loan goes deeper. Plug in five years, ten years, and thirty years. If the same loan wins at all three, you have your answer.
What to Ask Before You Sign
Walk into the conversation with four questions and you’ll avoid most of the regret. How much does one point actually reduce my rate — not in theory, in this specific quote? What is my breakeven month? How long do I genuinely expect to keep this loan? And if I paid zero points and invested the difference instead, what would that look like?
Get written answers to all four. Then trust the arithmetic over the sales pitch. A discount points calculator turns a vague feeling about “buying down the rate” into a specific number of months — and that number is the only thing that should decide whether you write that check at closing.