Mortgage Payoff Calculator
Estimate your monthly mortgage payment, total interest, payoff date, and how much time and interest you save with extra payments. Compare standard payoff versus accelerated payoff — instantly.
Quick preset
Loan details
Extra payments
Payment frequency
What to do next
Want to understand mortgage math in depth?
Step-by-step
What this calculator does
This mortgage payoff calculator runs two amortization simulations side by side: a standard payoff using only your base payment, and an accelerated payoff that applies your extra monthly amount and any annual lump sum directly to principal. It then reports the difference in months saved, total interest, and payoff date — giving you a clear picture of what each additional dollar actually buys in time and savings.
Formula used
The calculator uses the standard amortization payment formula, then simulates balance reduction period by period:
P = current loan balance
r = periodic interest rate (annual rate ÷ payments per year)
n = total remaining scheduled payments
In the accelerated scenario, extra payments are applied directly to the outstanding principal each period, shortening the simulation until balance reaches zero.
How to use
- Select a preset or enter your own loan balance, annual rate, and remaining term.
- Enter any extra monthly payment you can commit to. Start at $100–$200 if unsure.
- Add an annual lump sum if you make a yearly extra payment (e.g. from a bonus).
- Choose Monthly or Biweekly depending on your payment schedule.
- Click Calculate — the comparison bar and cards update instantly.
Example calculations
Base payment: $1,896
Saves ~4.5 years and ~$68,000 in interest.
Saves ~3 years and ~$28,000 in interest.
Saves ~10+ years and ~$150,000 in interest.
Saves ~3 years and ~$20,000 in interest.
Why extra mortgage payments matter
Mortgage interest is charged on the outstanding balance each period. This means interest is highest in year one and declines as you pay down principal. Extra payments made early in the loan — when the balance is largest — reduce the base on which interest is calculated for all future periods. The compounding effect works in reverse: every $100 extra today can eliminate far more than $100 of future interest.
The comparison bar above shows this visually. Even a modest extra monthly commitment ($100–$200) typically removes years from a 30-year mortgage and saves five to seven figures in interest over the life of the loan.
FAQ
How is the monthly mortgage payment calculated?
Using the standard amortization formula: Payment = P × r ÷ (1 − (1 + r)^−n), where P is the loan balance, r is the periodic rate (annual rate ÷ 12), and n is the number of remaining monthly payments. This gives a fixed payment that covers interest and principal simultaneously over the loan term.
What does "months saved" mean in the result?
Months saved is the difference between how long it takes to pay off with only your base payment versus paying off with the extra amounts included. If the calculator shows 54 months saved, you would reach a $0 balance 54 months earlier than your original schedule.
Where do I find my current loan balance and rate?
Your current balance (also called outstanding principal) appears on your monthly mortgage statement or in your lender's online portal. The annual interest rate is on your original loan documents or promissory note. If you have an ARM, use the current adjusted rate shown on your most recent statement.
Does one extra payment per year really help?
Often significantly. A single extra monthly payment per year on a 30-year mortgage typically reduces the total loan term by 4–5 years and saves tens of thousands in interest. This is why biweekly payment schedules (26 half-payments = 13 full payments per year) are popular — they achieve the equivalent of one extra monthly payment automatically.
Does this calculator include taxes and insurance?
No. This calculator covers principal and interest only — the core amortization math. Escrow, property taxes, homeowner's insurance, PMI, and HOA fees are separate costs that your lender rolls into your total monthly payment. Subtract those items from your total monthly bill to find the P&I portion to enter here.
Can my lender restrict extra principal payments?
Some mortgages have prepayment penalty clauses, especially within the first few years or on certain non-conforming loans. Always confirm with your servicer that extra funds will be applied directly to principal — not held for the next month's payment. Most conventional and FHA loans allow unlimited prepayment without penalty.
Related tools
Disclaimer: This mortgage payoff calculator provides planning estimates only. Actual payoff timing, total interest, and savings can vary based on lender compounding method, escrow adjustments, payment posting timing, fees, and whether extra payments are applied directly to principal. This tool does not constitute financial advice — consult your lender or a licensed mortgage professional before making payoff decisions.