Extra Mortgage Payment Calculator

When to round up

Use only the principal-and-interest portion of the mortgage payment. Confirm that the loan has no prepayment penalty and that the servicer applies extra money to principal. Escrow, fees, daily-interest timing, and servicer posting rules are not modeled.

When to use this calculator

• Comparing payments before committing
• Testing one financial input at a time
• Preparing questions for a lender, dealer, or budget review

Tips for better estimates

• Use the actual APR and loan term when available.
• Add taxes, insurance, fees, PMI, HOA, or maintenance when they apply.
• Treat the result as a planning estimate, not approval or a quote.

How this estimate was built

This page accrues interest monthly on the remaining fixed-rate mortgage balance, applies the scheduled principal-and-interest payment, then applies extra monthly principal and an optional annual principal payment after every twelfth interest charge. It compares that result with the scheduled-payment-only path without rounding the balance each month.

Worked example

Example inputs: Remaining mortgage balance: $300000; Interest rate: 6.5 %; Scheduled principal and interest payment: $1896.21 /month; Extra principal each month: $200 /month; Extra principal once per year: $0 /year. With those values, the calculator returns Save $103,446.52 and finish 6 years 11 months sooner. Estimated payoff falls from 30 years to 23 years 1 month with the entered extra principal payments.

Example scenarios

• On a $300,000 balance at 6.5% with a $1,896.21 principal-and-interest payment, $50 extra each month shortens the estimate by 2 years 2 months and saves about $33,580.88 in interest.
• On that same example loan, $100 extra each month shortens the estimate by 4 years and saves about $60,993.32 in interest.
• With $200 extra each month, the estimate falls from 30 years to 23 years 1 month, saving about $103,446.52 in interest.
• Instead of a monthly extra, one additional $1,896.21 principal payment after every twelfth interest charge shortens the estimate by 5 years 8 months and saves about $83,982.76 in interest.
• These examples use monthly interest and principal-only extra payments. A servicer's posting dates, daily interest, escrow, fees, and prepayment terms can change the actual schedule.

Quick reference chart

Common planning mistakes

Entering an escrow-inclusive payment instead of principal and interest, assuming extra money is automatically applied to principal, ignoring a prepayment penalty, and treating monthly-interest timing as an exact servicer schedule.