Formula
Each month: interest = opening balance × annual rate ÷ 12; principal paid = scheduled payment + extra principal − interest; new balance = opening balance − principal paid. Repeat until balance reaches zero.
Mortgage Payoff Calculator
Estimate how long a mortgage balance may take to pay off from current balance, interest rate, scheduled payment and extra monthly principal.
Worked example
For a $400,000 balance at 6.5% with a $2,528.27 scheduled payment and $250 extra principal, the calculator loops month by month until the balance reaches zero, then compares that result with the scheduled payment alone.
Professional note
Master’s Tip: compare the payoff estimate with an official lender payoff quote before sending a large extra payment. Interest posting dates and prepayment rules can change the exact figure.
Regional and unit assumptions
Standard or basis: fixed-rate monthly payoff projection using transparent amortization arithmetic. It is currency-neutral and not lender advice.
Assumptions and limitations
- The current balance is treated as the starting principal balance.
- The interest rate is fixed and converted to a monthly rate.
- Extra monthly payment is applied directly to principal with no prepayment penalty.
- Taxes, insurance, escrow, redraws, offset accounts, fees and payment posting delays are excluded.
Methodology & Accuracy
How this calculator is checked
CalculationTime pages are built around visible arithmetic: the formula, assumptions, worked example and practical limitations are shown so the result can be checked rather than simply trusted.
Formula used
Each month: interest = opening balance × annual rate ÷ 12; principal paid = scheduled payment + extra principal − interest; new balance = opening balance − principal paid. Repeat until balance reaches zero.
Standard or basis
Standard or basis: fixed-rate monthly payoff projection using transparent amortization arithmetic. It is currency-neutral and not lender advice.
Where a calculator follows a named legal, trade or industry standard, that standard is cited visibly. Otherwise the page uses transparent general arithmetic and states its limits.Master's Tip
Master’s Tip: compare the payoff estimate with an official lender payoff quote before sending a large extra payment. Interest posting dates and prepayment rules can change the exact figure.
Related calculators
Questions
How do I calculate mortgage payoff time?
Start with the current balance, add monthly interest, subtract the scheduled payment and any extra principal, then repeat until the balance reaches zero.
Do extra payments save interest?
They can when the lender applies them directly to principal and there is no prepayment penalty. This calculator shows a simple comparison.
Why does my lender payoff quote differ?
Lender payoff quotes can include daily interest, payment posting dates, fees, escrow, offset accounts and prepayment rules that are outside this public estimate.
Should I enter taxes and insurance?
No. Use the scheduled principal-and-interest payment. Taxes and insurance do not usually reduce principal.
What if my payment is too low?
If the total monthly payment does not cover first-month interest, the balance will not amortize and the calculator warns that the payment is too low.
Calculation note
Mortgage payoff planning is amortization turned into a deadline. Extra principal changes the future path because every later month starts from a smaller balance.
The loan amount comes first
The calculator separates home price and down payment because buyers often compare properties by price, while the payment formula needs the actual borrowed principal. Keeping both figures visible makes the printable report easier to review later.
Monthly payments are an annuity calculation
A fixed-rate mortgage payment is built so each payment covers that month’s interest and pays down some principal. Early payments carry more interest; later payments carry more principal as the balance falls.
Taxes, insurance and lender rules are separate layers
A household budget usually needs more than principal and interest. The optional tax and insurance fields keep those amounts visible, but they are simple monthly additions rather than a legal escrow or APR model.
Rate sensitivity is the useful comparison
The same loan can look affordable or stretched under different rates. Showing nearby rates helps the page beat generic calculators by making the risk of rate assumptions visible before the estimate is printed.