To calculate discount points on a mortgage, multiply your loan amount by the number of points and then by 0.01 to get the upfront cost, subtract the rate reduction from your quoted interest rate to find your new rate, and divide the upfront cost by your monthly payment savings to see how many months it takes to break even. One point equals 1% of the loan amount and typically lowers the interest rate by about 0.25%, though the exact reduction varies by lender.1My Home by Freddie Mac. What You Need to Know About Discount Points The math itself is simple. The judgment call is whether the trade-off fits how long you plan to keep the loan.
The Numbers You Need First
Every figure comes from the Loan Estimate your lender provides after you apply. Pull three items from it: the loan amount (the principal you’re borrowing, not the sale price), the par rate (the interest rate offered before any point adjustments), and the point-to-rate ratio (how much the rate drops per point).
That ratio matters more than most borrowers realize. A quarter-point reduction per point is a common quote, but it isn’t fixed. A different lender, or the same lender in a different market, may offer more or less rate reduction for the same 1% cost.1My Home by Freddie Mac. What You Need to Know About Discount Points Use the ratio your lender actually quotes rather than a rule of thumb, because a small difference in that number changes your break-even by months.
Step One: The Upfront Cost
Multiply the loan amount by the number of points, then by 0.01. On a $400,000 mortgage with two points:
$400,000 × 2 × 0.01 = $8,000
That $8,000 is due at closing on top of your other settlement costs. Fractional points work the same way. Half a point on the same loan costs $2,000 and cuts your rate by roughly half whatever per-point reduction your lender quoted. Buying partial points lets you fine-tune the balance between cash at closing and monthly savings.
Step Two: Your New Rate and Monthly Savings
Subtract the total rate reduction from the par rate. If your lender cuts the rate 0.25% per point and you buy two points, the total reduction is 0.50%. A 7.0% par rate becomes 6.5%.
Run both rates through a standard amortization calculation for your loan amount and term. On a $400,000 loan over 30 years, the monthly principal-and-interest payment at 7.0% is roughly $2,661. At 6.5%, it drops to about $2,528. The $133 difference is your monthly savings from the two points. Any online mortgage calculator will do this arithmetic instantly, but the inputs are what drive the answer: loan size, term, par rate, and point-to-rate ratio.
Step Three: The Break-Even Point
Divide the upfront cost by the monthly savings:
$8,000 ÷ $133 = about 60 months, or 5 years
Every payment you make past month 60, at the lower rate, is money ahead. Sell or refinance before month 60 and you paid more for the points than you got back. This is the single most important number in the analysis. A break-even period of two to three years makes points a near-automatic win for most buyers. A break-even stretching past seven or eight years should give you serious pause.
When the Simple Break-Even Understates Your Risk
The calculation above assumes you keep the same mortgage for the full comparison period. Real life often intervenes.
- Selling earlier than planned. Job changes, family needs, or a shifting housing market can push you out before break-even. If you sell at month 40 of a 60-month window, you spent $8,000 to save roughly $5,320.
- Refinancing before break-even. If rates drop enough after you close, refinancing may save more than your bought-down rate does. The points money already went into a loan you’re replacing. When rates trend downward, that risk is real.
- Adjustable-rate mortgages. On an ARM, buying points typically reduces only your initial fixed-rate period, not the rate for the full loan term. That shortens the window during which savings accumulate, and you should run the break-even using only the initial period length rather than 30 years.2Consumer Financial Protection Bureau. Consumer Handbook on Adjustable-Rate Mortgages
- Opportunity cost. The $8,000 is also cash you didn’t use elsewhere. A larger down payment could eliminate private mortgage insurance or shrink the loan enough to produce comparable savings. Comparing points against other uses of the same money often reveals a better option.
Lender Credits Run the Same Math in Reverse
Lender credits are the mirror image of discount points. Instead of paying cash to lower your rate, you accept a higher rate and the lender applies a credit against your closing costs.3Consumer Financial Protection Bureau. How Should I Use Lender Credits and Points (Also Called Discount Points)? You may see them called negative points on a lender worksheet.
The arithmetic is identical, just flipped. One point of lender credit on a $400,000 loan is $4,000 toward closing, in exchange for a rate increase (often around 0.25% per point, though this varies). Your monthly payment rises, but you bring less cash to the table. Credits make sense when you’re short on closing funds or don’t expect to keep the mortgage long enough for a lower rate to pay off. Calculate them side by side with discount points to see the full range of cost-versus-rate options your lender is offering.
How Taxes Shorten the Effective Break-Even
Discount points are prepaid interest, and the IRS lets you deduct them if you itemize. On a purchase, you can generally deduct the full cost of points in the year paid, provided the loan is secured by your main home, the points are calculated as a percentage of the loan amount, the amount is shown on the settlement statement, and the funds you brought to closing at least equal the points charged.4Internal Revenue Service. Publication 936, Home Mortgage Interest Deduction
Refinance points are different. They’re generally deducted gradually over the loan term rather than all at once.5Internal Revenue Service. Topic No. 504, Home Mortgage Points On a 30-year refinance with $6,000 in points, that’s $200 a year for 30 years. If part of the refinance goes toward substantially improving your main home, the portion tied to that improvement can be deducted in full the year paid.4Internal Revenue Service. Publication 936, Home Mortgage Interest Deduction
None of this helps unless your total itemized deductions exceed the standard deduction. For 2026, the standard deduction is $16,100 for single filers and $32,200 for married couples filing jointly.6Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026 A borrower who can deduct $8,000 in points recovers part of that cost through lower taxes, which shortens the effective break-even. A borrower taking the standard deduction gets no such adjustment, and the raw calculation stands as-is.
The Federal Cap You Probably Won’t Hit
For a loan to qualify as a “qualified mortgage” under federal law, total points and fees cannot exceed 3% of the loan amount.7Office of the Law Revision Counsel. 15 USC 1639c – Minimum Standards for Residential Mortgage Loans That 3% includes origination fees, not just discount points, so how much room you have depends on what the lender is already charging.
There’s a carve-out. The law allows up to two bona fide discount points to be excluded from the 3% calculation if the rate before the discount is no more than 1 percentage point above the average prime offer rate. Above that threshold, only one point can be excluded.7Office of the Law Revision Counsel. 15 USC 1639c – Minimum Standards for Residential Mortgage Loans Most buyers purchasing one or two points on a competitively priced loan won’t bump into the cap. If you’re considering three or more points, or your origination fees are already high, ask your lender how close you are.
If the Seller Is Paying
Sellers can pay for your discount points as part of a negotiated deal, but loan programs limit how much they can contribute. On conventional loans backed by Fannie Mae, the cap depends on your loan-to-value ratio: up to 3% of the sale price when LTV is above 90%, up to 6% when LTV is between 75.01% and 90%, up to 9% when LTV is 75% or below, and up to 2% on investment properties regardless of LTV. Those caps cover all seller contributions combined, not just points.8Fannie Mae. Interested Party Contributions (IPCs) FHA loans allow up to 6% in seller concessions. VA loans cap certain concession types at 4%, though standard closing costs the seller covers don’t count toward that figure. Any contribution above the applicable limit gets deducted from the sale price before the lender calculates your loan amount.
When the seller pays, the break-even calculation still matters for understanding how the lower rate affects your monthly payment. The urgency just shifts, because the cash didn’t come out of your pocket.