Mortgage Payoff Calculator
Payoff planning starts with a direct question: if you keep the current loan but send extra principal, when does the balance reach zero and how much interest disappears? This mortgage payoff calculator answers that question from the current balance forward. It estimates the required scheduled principal-and-interest payment, builds a normal payoff schedule, builds an accelerated schedule with your extra monthly and one-time payments, and reports the new payoff time, interest saved, months saved, and new total interest.
This page is intentionally narrower than the mortgage refinance calculator. A refinance replaces the loan and adds closing-cost break-even analysis. A payoff plan keeps the loan and attacks principal. It is also different from the mortgage with extra payments calculator, which is designed around original-loan and annual-extra scenarios. Here the emphasis is a practical countdown from the balance and remaining term you have now. For a full schedule view, use the mortgage amortization calculator, and for a baseline home-loan payment use the mortgage calculator.
What to enter
Use the current mortgage balance shown on your most recent statement. Enter the annual interest rate and the remaining term in years. If your servicer gives remaining months instead of years, divide by 12 and use the nearest half year if needed. Add the extra monthly payment you plan to send every month. Add a one-time extra payment only if you expect a lump sum, such as a bonus, sale proceeds, or savings transfer. The “apply one-time payment after” field controls timing: month 1 means the lump sum is applied with the first simulated payment.
The result labeled scheduled monthly payment is the principal-and-interest payment required to amortize the entered balance over the remaining term at the entered rate. The new monthly payment is that scheduled amount plus the recurring extra monthly amount. The one-time payment is not included in the new monthly payment display because it occurs only in the month you specify.
Mechanics and formula
The calculator first computes the scheduled payment:
P is the current balance, i is the monthly interest rate, and n is the remaining number of monthly payments. It then simulates each month. Interest is charged on the opening balance. The payment and any extra principal reduce the balance. In the one selected month, the lump sum is also applied.
The original schedule and accelerated schedule are compared:
If the added payments are large enough to retire the loan before a normal payment is due, the final payment is capped at the remaining balance plus interest. The model stops when the balance is effectively zero.
Checking a mortgage payoff scenario
Assume a current mortgage balance of $100,000, an annual interest rate of 4.5%, and 25 years remaining. You plan to pay an extra $100 every month, with no one-time extra payment. The remaining term is 300 months. The scheduled principal-and-interest payment is $555.83.
With no extra principal, the normal schedule lasts 300 months and produces about $66,749.74 of interest. With the extra $100 every month, the new monthly outflow is $655.83. The accelerated schedule reaches payoff in 227 months, which is 18 years and 11 months. The new total interest is about $48,609.55. Interest saved is $18,140.20, and the time saved is 73 months.
The example also shows why timing matters. The extra $100 is not just $100 less debt in a single month. It lowers the balance, so the next month starts with less principal earning interest. That compounding reduction repeats across the remaining loan until later scheduled payments are no longer needed.
When a payoff plan helps
A payoff plan can be appealing when the mortgage rate is higher than the safe return you expect from idle cash, when you want a guaranteed reduction in interest, or when being debt-free by a specific date matters. Borrowers often test the amount needed to finish before retirement, before a child starts college, or before a planned move. If the result shows a target date that is close but not quite early enough, increase the extra monthly amount or move a one-time payment earlier and compare again.
The trade-off is liquidity. Money sent to principal becomes home equity. It may reduce risk, but it is less accessible than cash in a savings account. If you lack an emergency fund, carry higher-rate credit-card debt, or receive an employer retirement match, those priorities may compete with mortgage payoff. Use the savings goal calculator to plan a cash reserve and the loan calculator to compare other amortized debts.
Practical tips
Tell the servicer that extra money should be applied to principal. Some payment portals have a separate principal-only field; others require a note or a different payment workflow. If the servicer holds partial payments until the next due date, the interest savings may not match this estimate. Confirm whether there are prepayment penalties, payoff statement fees, or limits on extra principal. Many mortgages do not have penalties, but the contract controls.
Keep the regular payment current. Extra principal does not replace the required payment unless the lender has explicitly recast or modified the loan. If your payment includes escrow, continue budgeting for taxes and insurance even as principal falls. This calculator is for education and planning; it is not financial advice or a payoff quote. A formal payoff statement from the servicer is still needed before closing out a loan.
Sources
- CFPB, Mortgages — borrower guidance for mortgage payments and loan management.
- CFPB, What is a mortgage prepayment penalty? — explanation of prepayment penalty concepts.
- Freddie Mac, My Home: Owning — homeowner education resources for managing a mortgage.
- Federal Reserve, A Consumer’s Guide to Mortgage Refinancings — context on payoff, refinancing, and cost comparisons.