See how much faster you can pay off your mortgage and how much interest extra payments save.
Two amortization schedules on the same loan: one at the required payment, one at the required payment plus whatever extra you can add. The difference between them is the interest you never pay and the years you get back. The default loan is $320,000 at 6.5% with a $2,023 monthly payment, which is a 30-year schedule, and the default extra is $200.
The result is not intuitive until you see it. $200 a month, which is $2,400 a year, removes six years and seven months from the schedule and saves $105,287 of interest. You pay $56,200 in extra principal to avoid $105,287 in interest, a return of 1.87 dollars saved for every dollar added.
The mechanism is that mortgage interest is charged on the outstanding balance every month, and it is front-loaded because the balance is largest at the start. On a $320,000 loan at 6.5%, the first payment of $2,023 contains $1,733 of interest and only $290 of principal. An extra $200 in month one is worth more than an extra $200 in month 300, because the first one avoids interest for 359 months and the second avoids almost nothing.
This is also why the interest saved is not linear in the extra payment. It is roughly proportional to the extra amount times the remaining months, and both terms shrink together as the loan ages. Someone who starts paying extra in year twelve gets a fraction of the benefit of someone who starts in year one.
$320,000 at 6.5% accrues $1,733.33 of interest in month one. The $2,023 payment leaves $289.67 of principal, so the balance becomes $319,710.33. Add the $200 and the balance becomes $319,510.33. Nothing dramatic happens in that month. The drama is the sum of 281 such months instead of 360.
| Extra per month | Payoff time | Time saved | Interest saved |
|---|---|---|---|
| $0 | 30 yr 0 mo | — | — |
| $200 | 23 yr 5 mo | 6 yr 7 mo | $105,287 |
| $500 | 18 yr 0 mo | 12 yr 0 mo | $185,341 |
| $1,000 | 13 yr 2 mo | 16 yr 10 mo | $251,149 |
Each additional dollar of extra payment has diminishing returns in percentage terms but not in absolute ones. Going from $200 to $500 triples the monthly commitment and adds $80,054 of interest saved. Going from $500 to $1,000 doubles it again and adds $65,808. The first $200 carries the best ratio, which is the practical argument for starting with a number you can sustain rather than waiting to afford a bigger one.
Most payoff calculators assume the extra payment runs for the life of the loan. Real households rarely work that way. People pay extra while a child is in daycare, or during a stretch of overtime, then stop. The table below answers the question those calculators skip: does a short burst of extra payments still matter?
The loan is $320,000 at 6.5% over 30 years, base payment $2,023, with $200 extra each month for a limited window and nothing after.
| Extra payment window | Total extra paid | Payoff time | Time saved | Interest saved |
|---|---|---|---|---|
| 12 months | $2,400 | 29 yr 5 mo | 7 months | $13,505 |
| 24 months | $4,800 | 28 yr 10 mo | 14 months | $25,423 |
| 60 months | $12,000 | 27 yr 4 mo | 32 months | $53,569 |
| 120 months | $24,000 | 25 yr 8 mo | 52 months | $82,720 |
Twelve months of $200 costs $2,400 and returns $13,505 of avoided interest, a ratio of better than five to one. That is the strongest return in the table, and it does not require a decade of discipline. A single year of discipline is enough to matter.
The reason is that interest is charged on the balance, and every dollar of early principal removes all the interest that dollar would have generated for the remaining 29 years. A dollar sent in year one saves roughly 29 years of interest. The same dollar sent in year 25 saves five. This is why stopping is not the same as never starting, and why the first burst of extra payments is worth more than the last.
Run the same $200 against a 4% mortgage and the picture changes completely.
| Loan rate | Payoff with $200 extra | Time saved | Interest saved |
|---|---|---|---|
| 4.0% | 16 yr 5 mo | 2 yr 5 mo | $18,851 |
| 6.5% | 23 yr 5 mo | 6 yr 7 mo | $105,287 |
At 4%, every extra dollar saves about $0.48 of interest. At 6.5% it saves about $1.87. That is the whole argument, and it explains why advice written during the 3% mortgage era was skeptical of prepayment: at that rate, prepaying was a guaranteed 3% return competing against a 4% savings account. At 6.5% the same advice inverts.
The decision is a comparison, not a rule. Paying down a 6.5% mortgage is a risk-free 6.5% return, and that is hard to beat with bonds. Whether it beats stocks depends on your horizon and your tolerance for a decade like 2000 through 2009. What it definitely beats is a savings account paying less than the mortgage rate, which is the most common place this money actually sits.
Lenders market biweekly payments as a special product. The arithmetic is simpler than the marketing. Twenty-six half-payments equal thirteen full payments a year, which is one extra monthly payment annually. On the default loan that is $2,023 spread over twelve months, or $168.58 a month, and the result is a payoff in 24 years and 2 months with about $93,000 of interest saved.
You can get the same outcome without a biweekly program by adding one twelfth of your payment to each monthly payment. That version requires no enrollment, no fee, and no third party holding your money for two weeks. Some biweekly services charge a setup fee and a per-transaction charge for a result you can reproduce with a standing instruction to your servicer.
Three ways to send the same $2,023 of extra principal a year, and they do not land in the same place. The biweekly trick from the section above spreads one extra monthly payment across the year at $168.58 a month. A second household writes one check for $2,023 every December, out of a bonus or a tax refund. A third skips the schedule entirely and sends a single $10,000 lump sum the day the loan starts. Same default loan: $320,000 at 6.5% over 30 years, base payment $2,023.
| Extra payment style | Payoff time | Interest saved |
|---|---|---|
| $168.58 extra every month | 24 yr 2 mo | $92,956 |
| $2,023 lump sum once a year | 24 yr 4 mo | $89,470 |
| $10,000 lump sum, once, in month one | 27 yr 5 mo | $53,879 |
The monthly spread beats the annual check by about $3,500, for one unromantic reason: the money reaches the balance weeks earlier on average, so it blocks that many more months of interest. If your income arrives in one annual bump, the once-a-year check is still a fine answer; the gap is small enough that consistency beats timing.
The lump sum row teaches the sharper lesson. $10,000 sent once at the start of the loan removes 31 months from the schedule and saves $53,879 of interest. Send the identical $10,000 five years later and the same payment saves $37,498 and 23 months. The money did not change; the remaining loan term it can poison with savings did. Every windfall question, a bonus, an inheritance, a refinancing cash-out in reverse, has the same answer embedded in it: the earlier the extra principal lands, the more interest it kills. The one-time case is easy to price directly in the calculator above by setting the extra field to your lump sum and reading the interest saved, then comparing it with the schedule the monthly version produces.
That it goes to principal. Most servicers apply extra to principal automatically, and some treat it as an early installment for the next month, which produces no interest savings at all. The statement will show whether the principal balance fell by the extra amount. If it did not, call and ask them to reapply it.
Whether you have PMI. Private mortgage insurance is charged when the down payment is under 20%, and it typically costs 0.5% to 1.5% of the loan annually. The Homeowners Protection Act requires automatic termination at 78% loan-to-value and lets you request removal at 80%. Paying the balance down to that threshold is often a larger return than the interest savings, because it removes an entire insurance premium.
Whether the money is needed for anything else first. A mortgage prepayment is illiquid. Home equity cannot pay for a layoff, and borrowing it back costs a new loan at current rates. Three to six months of expenses in cash should exist before extra principal becomes a monthly habit, and the emergency fund calculator sizes that number.
Refinancing lowers the rate on the whole balance. Prepaying attacks the balance at the existing rate. When rates have fallen by a full point or more and you plan to stay in the home long enough to clear the closing costs, the refinance break-even calculator answers the question directly. When rates have risen and you are holding a low-rate loan, extra principal is the only lever left, and its value is capped by how low that rate is.
Both belong next to the amortization calculator, which shows the interest and principal split of every payment and makes the front-loading visible. And if the question is really whether to buy at all, the rent versus buy calculator prices the whole decision rather than one loan.
A mortgage payoff is a schedule problem, and three tools break it into parts. The amortization calculator shows where each payment goes before any extra is applied. The refinance break-even calculator handles the rate side of the same decision. And the mortgage points calculator covers the third option, paying up front to lower the rate instead of paying monthly to lower the balance. The loan payment calculator fills in the payment itself and shows how much of an early extra payment reaches principal in the first years.
Start with an amount you will not cancel in a bad month. $200 on a $320,000 loan removes six and a half years and saves about $105,000, which is a large result from a modest commitment. Above that, the ratio of interest saved to dollars added falls with each increase, so the second $200 is worth less than the first.
Compare the mortgage rate against the expected after-tax return of the investment. A 6.5% mortgage is a guaranteed 6.5% return, which beats investment-grade bonds and competes with stocks on a risk-adjusted basis. A 3% mortgage is a guaranteed 3%, which does not. The comparison should use after-tax numbers on both sides, since mortgage interest may be deductible and investment gains will be taxed.
No. Extra principal shortens the term and leaves the required payment unchanged, which is exactly what makes it work. Some lenders offer a recast, which re-amortizes the remaining balance over the original term and lowers the payment, but that reverses most of the interest benefit. If your goal is a smaller payment rather than a shorter term, a recast or a refinance is the right tool.
A paid-off house lowers the income needed in retirement, which lowers both the portfolio requirement and the tax bill. It also removes sequence risk from the largest fixed expense in most budgets. The counterargument is liquidity: money in the house cannot be spent gradually. A common compromise is to enter retirement with enough liquid assets to cover several years of expenses and let the mortgage run if the rate is low.
Because interest is charged on the outstanding balance, and the balance is at its largest at the start. On a 6.5% loan the first payment is 86% interest. The crossover, where principal exceeds interest, arrives in month 233, or year 19. This is a feature of amortization rather than a trick, and it is the reason early prepayments are so valuable.
The monthly version wins slightly. On a $320,000 loan at 6.5%, sending $168.58 of extra principal every month (one extra payment spread over twelve) saves $92,956 and pays off in 24 years 2 months, while a single $2,023 check each December saves $89,470 and pays off two months later. The gap exists because monthly money reaches the balance earlier and blocks more months of interest. If your income genuinely arrives once a year, the annual check is close enough that consistency matters more than timing.
It shortens the term and leaves the required payment unchanged, and its value depends almost entirely on timing. A $10,000 lump sum sent in month one of a $320,000 loan at 6.5% removes 31 months and saves $53,879 of interest. The same $10,000 sent in month 60 saves $37,498 and 23 months. Late in the loan a lump sum is worth little, because there are few remaining months of interest for it to prevent. If you receive a windfall, send it when it arrives rather than saving it up.
Not directly. Paying down a mortgage lowers your overall debt and usually helps a score, though a closed mortgage account eventually shortens your credit history. The practical risk is liquidity rather than credit: money sent to principal is not available for anything else without a new loan or a sale, and a home equity line taken in an emergency costs more than the mortgage did.
All calculation logic on this page is implemented from the primary documents below. Each one is listed with the figure it supplies, so any rate or threshold in the result can be traced back to its published source.
Same published formulas, same sourcing standard, one page each.