Mortgage payoff calculator: extra payments and housing costs
See what extra principal could change, while keeping taxes and insurance visible in your budget. For an existing US fixed-rate mortgage.
Compare mortgage payoff plans
Example numbers only. Replace them with your own statement. All amounts are in US dollars. Nothing is calculated until you choose Compare.
Use a decimal point and up to two decimal places; no commas or currency symbols. Enter 0 for costs that do not apply.
The calculator is unavailable until its calculation files load. The manual worksheet and explanations below remain available.
Calculations run in this browser. This tool does not save or send your entries. No registration is needed.
Start with the payment you already owe
This tool answers one question: what changes if you put extra money toward an existing fixed-rate mortgage? It keeps the required principal-and-interest payment unchanged and compares paying it alone with paying recurring or one-time extra principal. A smaller balance can reduce future interest. The result does not promise a lower required bill; a lender-approved recast is a different process.
Find the right numbers on your statement
Use the unpaid principal balance, the contractual interest rate and the required principal-and-interest amount. If your monthly debit also includes taxes or insurance through escrow, do not put that full debit in the principal-and-interest box. Enter those costs separately in the budget section. The CFPB explains the payment components. If your statement is unclear, ask the servicer for the breakdown before comparing.
A manual worksheet you can use without JavaScript
Write down the opening principal. Estimate one month of interest as principal × annual rate ÷ 100 ÷ 12, rounded to cents. Add that interest to the balance. Subtract the required principal-and-interest payment, then any recurring extra and the one-time extra for that month; never subtract more than is owed. The amount left becomes next month’s starting balance. For a fictional $1,000 balance at 12%, interest is $10 in month 1. A $100 required payment leaves $910; a further $20 extra leaves $890. Keep taxes and insurance on a separate budget line. This simplified worksheet follows the model, not daily lender accounting.
Check these points before sending extra money
Ask the servicer whether additional principal is allowed, how to label the payment and whether a prepayment fee applies. The CFPB’s servicing guide describes extra-principal payments, and its prepayment-penalty explanation describes possible contract fees. Keep enough cash for bills, reserves and irregular expenses before committing to an extra payment. Use the debt comparison if other balances also compete for that cash.
How the estimate works and where it stops
Every month the model adds fixed-rate interest to the opening balance, rounded half-up to cents. It applies the required principal-and-interest payment first, then recurring extra, then the one-time extra, capping each at what remains owed. It stops when the balance reaches zero, after 1,200 months, or when a proposed payment does not reduce the balance. A partial result cannot show total lifetime savings. The model excludes daily interest, late fees, arrears, escrow shortages, rate changes, prepayment charges, automatic PMI cancellation, recasting and tax deductions. It is not suitable for an ARM, interest-only or balloon loan. Ask your servicer for an exact payoff quote.
If the required payment is already difficult
Extra payments are optional in this comparison. If you may miss the required payment, contact your mortgage servicer early and review HUD’s mortgage difficulty guidance. You can also find a HUD-approved housing counselor. The calculator cannot determine eligibility for assistance or negotiate your loan.