Home-loan repayment planning
Mortgage Payoff Calculator
See how extra monthly payments or a one-time lump sum may change your mortgage payoff date and total interest.
✓ Private✓ No registration✓ Browser-based✓ Educational estimates
Compare standard and accelerated payoff
Enter the outstanding balance and remaining term, not the original loan amount.
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Your calculation in plain English
What this mortgage payoff calculator does
This calculator compares a standard mortgage repayment schedule with an accelerated schedule that includes an extra monthly payment and an optional lump sum. It estimates the contractual monthly payment, total interest, payoff time, interest saved and time saved.
It is designed for fixed-rate educational modelling. Actual home loans may have changing rates, lock-in periods, prepayment restrictions or fees. Check the loan terms before making additional repayments.
How mortgage amortisation works
Each payment contains interest and principal. Interest is charged on the outstanding balance, so early payments often contain a larger interest component. As principal falls, less interest is charged and more of the payment reduces the balance.
An extra payment is applied directly to principal in the model. This reduces the balance used to calculate future interest, which can shorten the term and create savings over many later payments.
How to interpret the comparison
The standard monthly payment is the amount needed to amortise the balance over the remaining term at the entered rate. The accelerated payoff time assumes the same payment plus the extra amount. Interest saved is the difference between the two schedules.
Compare the mortgage saving with other uses of cash, including emergency reserves, high-interest debt and long-term investing. Mortgage repayment produces a return similar to the avoided interest rate, but it also reduces liquidity.
Common mistakes
- Entering the original loan amount instead of the current balance.
- Ignoring prepayment penalties or administrative fees.
- Using the current rate for a loan that may reprice later.
- Putting all spare cash into the mortgage without maintaining an emergency reserve.
- Comparing guaranteed interest savings with an assumed investment return as though the risks were identical.
Frequently asked questions
How is the monthly mortgage payment calculated?
It is the level payment required to amortise the outstanding balance over the remaining term at the entered rate.
Does an extra payment reduce the next monthly payment?
This model keeps the payment level and shortens the term. Your lender may apply prepayments differently.
Is a lump sum treated as immediate?
Yes. It is deducted from principal before the accelerated schedule begins.
What if my rate changes?
Run separate scenarios. This calculator assumes one rate for the remaining term.
Are prepayment penalties included?
No. Check your mortgage agreement.
Should I repay the mortgage or invest?
That depends on risk, liquidity, tax and expected returns. Compare the guaranteed interest saving with the uncertain return and liquidity of investing.
Why is the interest saving larger early in the loan?
There are more future periods in which the lower balance avoids interest.
Can the mortgage be paid off too quickly in the model?
The model caps the final payment at the remaining balance and interest due.
Continue your financial journey
Financial disclaimer: This calculator and guide are provided for educational information only. They do not constitute financial, investment, tax or legal advice. Actual outcomes will vary.