What a 1-Point Mortgage Rate Drop Actually Changes
A $300,000 mortgage dropping from 7% to 6% saves about $200 a month, and roughly $70,000 in interest over 30 years. From one percentage point. But that number only holds if the borrower keeps the loan for all 360 payments, so what happens to the math for everyone else, the people who sell, move, or refinance first? That's the question this post actually works through, using the same loan examples throughout.
- A 1% rate drop saves roughly $60 to $70 per month for every $100,000 borrowed on a 30-year fixed mortgage.
- On a $300,000 mortgage, dropping from 7% to 6% saves about $195 to $210 a month.
- Over the full 30-year term, that same $300,000 loan saves roughly $70,000 in total interest.
- A typical U.S. home valued at $368,720 sees a payment drop from $1,962 to $1,913 with just a 0.25-point move (7% to 6.75%), saving $17,744 over 30 years.
- Buyers in high-cost markets like San Diego feel a full 1-point drop much more in dollar terms than buyers in cheaper markets do, because the savings from a rate cut scale with the size of the loan. Bigger loan, bigger payoff from the same percentage move.
The core mechanism here is compounding interest working in reverse: a lower rate means less of each payment goes to interest and more goes to principal, which shrinks the balance faster and cuts the total interest charged across 360 monthly payments. That number, 360, is the fixed horizon every savings estimate above assumes. It's also the assumption the next section tests against what actually happens when someone buys a home, pays points, or refinances before year 30.
How the Rate Gap Affects Buying Power and Refinancing Math
The numbers above show what a rate drop is worth over a full 30-year term. But rate changes don't just affect existing homeowners riding out a loan to its end. They change how much home a buyer can afford on the same monthly budget, and they decide whether paying upfront for a lower rate, or refinancing into one, actually pays off before that 30-year horizon arrives. Anyone budgeting around a fixed monthly payment should think in terms of purchasing power, not sticker price.
- A buyer budgeting $1,962 a month, the same payment level used in the typical-home example above, could afford noticeably more home if rates fell from 7% to 6%, without raising the payment, since a lower rate stretches the same monthly budget further.
- Buying two discount points for $8,000 upfront on a loan can lower the monthly payment by $133 and save $47,858 in interest over 30 years. But only if the borrower stays in the home the full term and never refinances.
- Take a refinance example: a $400,000 loan at 7.40% costs $2,769 a month. After two years of paydown to roughly $392,000, refinancing into a new 30-year loan at 6.30% drops the payment to about $2,426, a savings of $333 a month, or over $4,000 a year.
- Closing costs on that refinance, at roughly 2% of the new balance, run about $7,800, and that eats into the monthly savings until the borrower hits the breakeven point. Until then, the total interest saved versus the original loan is smaller than the monthly savings number makes it look.
The refinancing math carries a catch: restarting a 30-year term after two years of payments means the borrower is financing close to the original $400,000 amount again, just at a lower rate, which stretches out the payoff timeline even as it lowers the monthly bill. Discount points carry a similar tradeoff in the other direction. Paying $8,000 upfront only saves the full $47,858 if the homeowner never sells, never refinances, and rides out the entire 360-month schedule. Move before then, through a sale, a job relocation, or a later refinance into an even lower rate, and that upfront points payment may never fully pay for itself.
Permanent rate buydowns and temporary rate buydowns produce very different outcomes for exactly this reason. A permanent buydown, using points, lowers the rate for the life of the loan, so the savings calculated above hold for all 30 years. A temporary buydown lowers the rate for only the first year or two, then reverts to the original note rate, so the long-term interest savings shown in these examples never materialize past that short window. For anyone comparing offers, the practical move is to run the breakeven math on points and refinance costs against actual expected time in the home, not the full 30-year horizon, since few borrowers hold the same loan for all 360 payments. That's the answer to the question this post opened with: the $70,000 and $47,858 figures are real, but they're ceiling numbers that assume a borrower who never moves and never refinances. The number that matters more for most households is the monthly savings figure, $333 a month in the refinance example above, because that's what actually shows up in the bank account every month, whether the borrower stays for 3 years or 30.