Mortgage Prepayment Calculator
Enter your mortgage, then add an extra amount to each monthly payment. The calculator amortizes both schedules side by side and shows the months and interest your overpayment saves.
Your mortgage
What overpaying saves
Interest saved
$69,082
and 4 yr 6 mo off the term
- Normal payment
- $2,160.66
- With extra
- $2,360.66
- Payoff without extra
- 25 yr
- Payoff with extra
- 20 yr 6 mo
Adding $200 to each payment clears the mortgage in 20 yr 6 mo instead of 25 yr, cutting total interest from $328,199 to $259,117 — a saving of 21%.
Worked example
A 320,000 mortgage at 6.5% over 25 years costs about 2,160 a month and roughly 328,000 in interest. Add 200 to every payment and the balance falls faster: the loan clears in about 21 years and 8 months, and total interest drops by roughly 50,000.
How prepayment saves money
Each month interest is charged on the outstanding balance only. The scheduled payment covers that interest first, and the rest reduces principal. Anything extra you pay goes 100% against principal, so every later month is charged interest on a smaller balance — the saving compounds and the schedule ends early.
Frequently asked questions
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Disclaimer: Calcemitool provides general estimates for information only — this is not financial, tax or investment advice. Real returns, exchange rates and lender charges vary. Confirm any figure with your lender or a qualified adviser before acting on it.