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The 2026 mortgage payoff study
How much does a 30-year mortgage really cost — and how much do extra payments actually save? We ran the numbers across rates, extra amounts, and loan sizes. All figures are computed, not estimated.
By the PayoffSchedule Editorial Team · Data computed with our tested amortization engine · Free to cite with a link to this page.
Key findings
- On a $400,000 mortgage at 6.5% over 30 years, you pay about $510,178 in interest — that's 128% of the amount you borrowed, on top of the loan itself.
- The monthly payment is about $2,528.27, and you repay roughly $910,178 in total.
- Adding just $200 a month cuts the interest by about $111,892 and pays the loan off 5 yr 7 mo early.
- At $500 a month extra, the savings jump to about $205,557 and 10 yr 7 mo.
1. The lifetime cost of a $400,000 mortgage, by interest rate
Same loan, same 30-year term — only the rate changes. Notice how total interest can exceed the loan amount itself.
| Rate | Monthly payment | Total interest | Total repaid |
|---|---|---|---|
| 4% | $1,909.66 | $287,478 | $687,478 |
| 4.5% | $2,026.74 | $329,627 | $729,627 |
| 5% | $2,147.29 | $373,023 | $773,023 |
| 5.5% | $2,271.16 | $417,616 | $817,616 |
| 6% | $2,398.20 | $463,353 | $863,353 |
| 6.5% | $2,528.27 | $510,178 | $910,178 |
| 7% | $2,661.21 | $558,036 | $958,036 |
| 7.5% | $2,796.86 | $606,869 | $1,006,869 |
| 8% | $2,935.06 | $656,621 | $1,056,621 |
2. How much extra payments save ($400,000 at 6.5%)
Starting from day one, a fixed extra amount added to every payment:
| Extra / month | Interest saved | Time saved | Interest still paid |
|---|---|---|---|
| $100 | $63,917 | 3 yr 2 mo | $446,261 |
| $200 | $111,892 | 5 yr 7 mo | $398,286 |
| $300 | $149,581 | 7 yr 7 mo | $360,597 |
| $500 | $205,557 | 10 yr 7 mo | $304,621 |
| $1,000 | $288,297 | 15 yr 3 mo | $221,881 |
3. The same $200/month, across loan sizes (at 6.5%)
An extra $200 a month does more on a bigger loan, but it saves a meaningful sum at every size:
| Loan amount | Interest saved | Time saved |
|---|---|---|
| $250,000 | $97,618 | 7 yr 11 mo |
| $350,000 | $108,097 | 6 yr 2 mo |
| $450,000 | $115,050 | 5 yr 1 mo |
| $550,000 | $120,008 | 4 yr 4 mo |
Methodology
All figures are computed with PayoffSchedule.com's amortization engine using the standard loan-amortization model and verified against known results (see our editorial standards). Figures assume a fixed-rate, fully amortizing loan and exclude taxes, insurance and fees. They are illustrative, not a loan offer.
Cite this study: please credit "PayoffSchedule.com" with a link to this page. Journalists and writers welcome — questions to contact@payoffschedule.com.