One Extra Mortgage Payment a Year Calculator
See how making just one extra full mortgage payment each year shortens your loan and slashes total interest.
How it works
Each year one extra payment (= one monthly payment) is applied entirely to principal · Lower balance means less interest and an earlier payoff
One extra payment a year goes 100% to principal, because the month’s interest is already covered by the regular payment. That directly shrinks the balance every interest calculation depends on, so the effect snowballs: less interest this month leaves more principal knocked down next month. On a 30-year loan it typically removes four to six years and a large chunk of interest.
Worked example
A $300,000 balance at 6.5% over 30 years pays about $383,000 in interest on the standard schedule. Adding one extra $1,896 payment each year pays the loan off in roughly 25 years and cuts total interest by around $70,000 — from a single extra payment annually.
Frequently asked questions
How is this different from a biweekly plan?
It is nearly identical. A biweekly schedule quietly produces one extra payment a year; making that extra payment directly gives almost the same savings without any special billing setup, and you control exactly when it happens.
When should I make the extra payment?
Earlier in the year and earlier in the loan saves the most, because the extra principal avoids more future interest the longer it is working. But any time helps — even an irregular lump sum reduces interest.
Will my lender apply it to principal?
Only if you tell them to. Extra money can otherwise be treated as a prepayment of the next bill rather than a principal reduction. Mark the payment as principal-only and confirm it was applied that way.
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This is an educational estimate, not financial advice. Real results depend on rates, taxes, fees and market returns that no calculator can guarantee — confirm figures with your lender or a licensed advisor.