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Prepayment Calculator

Compare your original payoff with a lump sum, extra monthly principal, or biweekly payments.

Your loan

$
%

Illustrative example rate.

yrs

Optional. Leave at 1 if starting fresh.

Prepayment strategies

$

Added to every monthly payment.

$

Which payment # does the lump sum land on?

Prepayment summary

These prepayments pay the loan off 5 years, 4 months earlier and save about $113,223 in interest.

Headline outcomes

Interest saved$113,223
Months saved64 (5y 4m)
New payoff dateMay 1, 2051
Original payoff dateSeptember 1, 2056

Side-by-side

Original total interest$535,687
With prepayment interest$422,464
Original months360
With prepayment months296
Results are estimates based on user inputs and do not represent loan terms, APR, or a financing offer. Pre-filled values are illustrative examples, not available or quoted rates. Actual terms depend on credit, property, program, and underwriting. Every result applies to the entered planning scenario, not an observation period or local market statistic. Replace price, tax, insurance and fee allowances with dated, property-specific figures. Missing inputs are not assumed to be zero.

Original schedule vs with prepayment

Principal vs interest by year
Loan balance over time
YearPaymentsInterestPrincipalExtraBalance
Year 1 (2026)$8,564$6,816$1,148$600$418,252
Year 2 (2027)$34,256$26,972$4,884$2,400$410,967
Year 3 (2028)$34,256$26,484$5,372$2,400$403,195
Year 4 (2029)$34,256$25,964$5,893$2,400$394,902
Year 5 (2030)$34,256$25,408$6,448$2,400$386,054
Year 6 (2031)$34,256$24,816$7,041$2,400$376,613
Year 7 (2032)$34,256$24,183$7,673$2,400$366,541
Year 8 (2033)$34,256$23,509$8,348$2,400$355,793
Year 9 (2034)$34,256$22,789$9,067$2,400$344,326
Year 10 (2035)$34,256$22,021$9,835$2,400$332,090
Year 11 (2036)$34,256$21,202$10,655$2,400$319,036
Year 12 (2037)$34,256$20,327$11,529$2,400$305,107
Year 13 (2038)$34,256$19,394$12,462$2,400$290,245
Year 14 (2039)$34,256$18,399$13,457$2,400$274,388
Year 15 (2040)$34,256$17,337$14,519$2,400$257,468
Year 16 (2041)$34,256$16,204$15,652$2,400$239,416
Year 17 (2042)$34,256$14,995$16,861$2,400$220,155
Year 18 (2043)$34,256$13,705$18,151$2,400$199,604
Year 19 (2044)$34,256$12,329$19,528$2,400$177,676
Year 20 (2045)$34,256$10,860$20,996$2,400$154,280
Year 21 (2046)$34,256$9,293$22,563$2,400$129,317
Year 22 (2047)$34,256$7,621$24,235$2,400$102,682
Year 23 (2048)$34,256$5,838$26,019$2,400$74,263
Year 24 (2049)$34,256$3,934$27,922$2,400$43,941
Year 25 (2050)$34,256$1,904$29,953$2,400$11,589
Year 26 (2051)$11,751$162$10,789$800$0

Want to stress-test a prepayment plan?

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Frequently asked questions

How does a biweekly mortgage actually work?
You pay half a monthly payment every two weeks. There are 26 two-week periods in a year, so you end up making the equivalent of 13 monthly payments per year instead of 12. That extra payment goes to principal.
Is a lump sum or a recurring extra payment better?
Either works. A lump sum saves the most interest per dollar when applied early in the loan. Recurring extras are easier to budget. Mixing both lets you attack the balance from two angles.
Will my lender let me make extra principal payments?
On a standard U.S. mortgage, yes, with no prepayment penalty. Mark the extra as a principal-only payment so it applies to the balance, not toward next month's scheduled payment.
Should I prepay the mortgage or invest the money?
Compare your mortgage rate with what you could safely earn after tax. A higher mortgage rate favors prepaying; a materially lower rate can favor long-term investing. This calculator estimates interest savings only. You decide the trade-off.

Related glossary terms

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Related reading

Want the story behind the numbers?

  • ArticleHow much house can you actually afford?Make sure extra payments fit your overall budget.Read
    Try: Affordability
  • HubWhen to refinanceCompare prepay against a full refi at today's rates.Read
  • ArticleWhat actually moves mortgage rates (and what does not)Why prepaying is sometimes better than waiting on rates.Read
    Try: Refinance
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More advanced & tools calculators

See all

Amortization Calculator

See exactly how each payment splits between principal and interest, with a full month-by-month schedule.

Use amortization calculator

15 vs 30 Year Comparison

Compare a 15-year and a 30-year mortgage side by side. See the monthly difference and lifetime interest.

Use 15 vs 30 year comparison calculator

Points & Rate Buydown Calculator

Model discount points or a temporary 2-1 / 3-2-1 buydown. Break-even, monthly savings, and total subsidy.

Use points & rate buydown calculator

PMI Drop-Off Calculator

See exactly when your PMI will fall off at the 80% and 78% LTV thresholds, and how extra payments speed it up.

Use pmi drop-off calculator