Extra Mortgage Payment Calculator
Find out how much sooner you could own your home and how much interest you would save by paying a little extra each month, once a year or as a one-time lump sum.
| Without extra | With extra | Difference |
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Loan balance over time
Amortization schedule with extra payments
Yearly rows. Tap a year to see its monthly payments.
| Period | Payment | Extra | Principal | Interest | Balance | Balance without extra |
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Estimates only, not financial advice. Principal and interest only. Check that your lender applies extra payments to principal and has no prepayment penalty.
How to use the Extra Mortgage Payment Calculator
- Enter your mortgage: loan amount, interest rate, term in years and the month of the first payment.
- Add extra payments: an amount every month, an amount once a year (pick the month) and/or a one-time lump sum (pick the month).
- Press Calculate to see the interest saved, how many years and months sooner the loan is paid off, and the new payoff date.
- Compare the balance lines on the chart to see how the extra payments speed things up.
- Open the schedule to check every payment, or download it as CSV.
How extra payments are applied
Your regular payment is fixed by the loan formula M = P × r ÷ (1 − (1 + r)−n), where r is the annual rate ÷ 12 and n is the number of months. Each month the interest is the balance × r, and the rest of the payment reduces the balance. An extra payment goes straight to principal, so next month's interest is smaller and more of every later payment goes to principal too.
Example: $300,000 at 6.5% for 30 years gives r = 0.065 ÷ 12 ≈ 0.0054167 and M = $1,896.20. In month one, interest is $1,625.00 and only $271.20 reduces the balance. Add $200 extra and the principal paid that month almost doubles to $471.20.
What extra payments save on a $300,000 loan at 6.5%
| Extra each month | Paid off in | Time saved | Total interest | Interest saved |
|---|---|---|---|---|
| $0 | 30 yrs | – | $382,637 | – |
| $100 | 26 yrs | 4 yrs | $321,641 | $60,996 |
| $200 | 23 yrs 1 mo | 6 yrs 11 mo | $279,187 | $103,450 |
| $500 | 17 yrs 6 mo | 12 yrs 6 mo | $202,875 | $179,762 |
| $1,000 | 12 yrs 9 mo | 17 yrs 3 mo | $141,472 | $241,165 |
Payments are rounded to the cent each month, as lenders do, so totals can differ by a few dollars from other calculators.
Tips for paying off a mortgage early
- Start early. Extra principal in the first years of a loan saves far more interest than the same amount near the end.
- Round up. Rounding $1,896.20 up to $2,000 is an easy habit that adds about $104 a month.
- Use windfalls. Put part of a bonus or tax refund toward a once-a-year extra payment.
- Keep a safety net first. Money paid into the house is hard to get back out, so keep an emergency fund and clear high-interest debt before paying extra.
The figures on this page are estimates only and are not financial advice.
Frequently asked questions
How much does an extra $200 a month save on a mortgage?
On a $300,000 loan at 6.5% for 30 years (regular payment $1,896.20), paying an extra $200 every month pays the loan off in 277 months instead of 360, almost 7 years sooner, and saves about $103,450 in interest.
Why do extra payments save so much interest?
Mortgage interest is charged on the remaining balance each month. Every extra dollar of principal you pay lowers the balance immediately, so all future interest is charged on a smaller amount. Extra payments made early in the loan save the most.
Is it better to pay extra monthly or once a year?
For the same total amount, paying monthly saves slightly more because the balance falls sooner. A yearly payment from a bonus or tax refund is still very effective. Making one extra full payment per year is roughly the same as biweekly payments.
Does paying extra lower my monthly payment?
Usually not. Your required payment stays the same and the loan simply ends sooner. Some lenders offer a recast after a large lump sum, which recalculates a lower payment over the remaining term, often for a small fee.
Should I tell my lender the extra is for principal?
Yes. Make sure the extra amount is applied to principal, not held for the next payment or used for escrow. Also check that your loan has no prepayment penalty.
Should I pay off my mortgage early or invest?
It depends on your mortgage rate, expected investment returns, taxes and how much you value being debt-free. Paying extra gives a guaranteed return equal to your interest rate. Build an emergency fund and pay off higher-interest debt first.