Mortgage Payoff Calculator: What Extra Payments Save
Extra and biweekly payments: interest saved and years cut.
Interest you save
$99,922
- Monthly P&I
- $1,869
- Interest paid
- $272,799
- Payoff date
- Oct 2049
+$200 extra avg
was $372,720
was Sep 2056
Paying about $200 a month extra saves $99,922 of interest — $4,329 a year for every year you pay. That's a guaranteed 6.36% return on each extra dollar.
Try a what-if
Your numbers
Your loan
$300,000
30 years left
$200 / month toward principal
A bonus or tax refund, paid at each 12-month mark.
$0 / year
Principal and interest only (taxes, insurance and PMI don't change the payoff). Biweekly = half your payment every two weeks, 13 full payments a year. Check that your servicer applies extra money to principal and charges no prepayment penalty.
Is a lower rate the better move? Check the refinance break-even calculator. Wondering whether to invest the extra instead? At 6.36% your payoff "return" is guaranteed — compare it with the investment calculator.
Next steps
On a $300,000, 30-year mortgage at 6.36%, paying an extra $200 a month saves about $99,922 in interest and pays the loan off 6 years and 11 months early. Switching to biweekly payments instead saves about $83,295 and 5 years 8 months. This mortgage payoff calculator shows what extra payments do to your loan: an extra amount every month, a lump sum once a year such as a bonus or tax refund, or biweekly payments — alone or combined. Start from your current balance and years left, or from your original loan and how long you've been paying. You'll see interest saved, time saved, your new payoff date and the balance over time on both schedules.
How this calculator works
- Enter your current loan balance and the years left — or switch to 'Original loan' and enter the amount, term and years already paid.
- Enter your interest rate. The default is the latest Freddie Mac 30-year average.
- Add an extra monthly payment toward principal.
- Optionally add a yearly lump sum (a bonus or refund) and turn on biweekly payments.
- Read the interest you save, how much sooner you're debt-free and your new payoff date, and compare the two balance lines on the chart.
payment = B × i ÷ (1 − (1 + i)^−n), i = APR ÷ 12
each month: interest = balance × i; balance ← balance + interest − (payment + extra)
biweekly ≈ + payment ÷ 12 each month (13 payments a year)The calculator runs the regular schedule and your accelerated schedule month by month on the same loan. Every extra dollar goes straight to principal, so less interest accrues the following month; the difference in total interest is what you save. Biweekly payments add one extra monthly payment per year.
- B
- Loan balance
- i
- Monthly interest rate (APR ÷ 12)
- n
- Months remaining
- extra
- Extra monthly, yearly and biweekly amounts
Frequently asked questions
How much does paying $200 extra a month save on a mortgage?
On a $300,000, 30-year loan at 6.36% (the Freddie Mac average), the principal-and-interest payment is $1,868.67. Adding $200 a month toward principal pays the loan off 6 years and 11 months early and saves about $99,922 in interest — total interest falls from about $372,720 to $272,799.
Are biweekly mortgage payments worth it?
Paying half your payment every two weeks means 26 half-payments, or 13 full payments a year instead of 12. On a $300,000 loan at 6.36%, that one extra payment a year cuts about 5 years and 8 months off a 30-year mortgage and saves roughly $83,295 in interest. Skip services that charge fees to do it.
What does an extra $100 a month do to a mortgage?
On a $300,000, 30-year mortgage at 6.36%, $100 a month extra saves about $58,786 in interest and pays the loan off 4 years early; $300 a month saves about $130,701 and 9 years 2 months. Extra money early in the loan saves the most, because it removes principal that would otherwise accrue interest for decades.
Should I pay off my mortgage early or invest?
Extra mortgage payments earn a guaranteed return equal to your rate — 6.36% on a typical 2026 loan — with no risk. Stocks have historically returned more (about 10% a year for the S&P 500) but with big swings. Most planners suggest capturing any 401(k) match and building an emergency fund first, then deciding by your rate and risk tolerance.
How do I make sure extra payments go toward principal?
Label the extra amount as 'principal only' in your servicer's online portal or on the check memo, then confirm on the next statement that the principal balance dropped by that amount. Check your loan documents for prepayment penalties (rare on modern mortgages), and avoid third-party biweekly programs that charge setup or processing fees.
Sources used in this calculator
Reviewed by the Money Scale editorial team. How we source our data
Related calculators
See all- Mortgage PaymentFull PITI + amortization + PMI cancellation date.
- Refinance Break-evenMonthly savings + month closing costs are recouped.
- Home AffordabilityHow much house you actually qualify for, given DTI rules.
- HELOCInterest-only draw + amortizing repayment phase.
- Debt PayoffAvalanche vs snowball: months saved and interest avoided.
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