Model an existing installment loan's payoff by entering its balance, annual rate, regular payment, and any monthly extra or upfront lump sum. The model applies the lump sum before its first modeled interest period, adds the recurring extra to each monthly payment, and uses annual rate divided by 12. The output is a projection, not a lender payoff quote: real payment timing, interest accrual, and payment application depend on your loan agreement and servicer.
How to Use the Loan Payoff Calculator
- Enter the loan facts: Type the Current Balance, choose the Currency, enter the Interest Rate (% p.a.), and type the Monthly Payment you make.
- Check the payment rule: The payment must be more than the first month's interest charge, otherwise the balance never clears.
- Add one-time money: Optionally set the Next Payment Due date to pin the payoff to a calendar date, and enter a One-Time Lump Sum that is paid once, straight off the principal.
- Use the extra toggle: Switch on Extra Monthly Payment and enter the "Amount added each month" to model a recurring extra on top of your payment.
- Calculate: Click Calculate to see Months to Pay Off, Total Interest, Principal Repaid, and the Estimated Payoff Date, plus the Interest Saved and Time Saved banner when an extra is used.
View Amortization Schedule lists every month's payment, principal, interest, and balance, but the output is a model, not a lender payoff quote.
How Extra Principal Disrupts the Amortization Curve
The calculator walks the balance month by month at the entered annual rate divided by 12. It compares the regular payment against a plan that also includes the monthly extra. A lump sum, if entered, is applied up front before the first modeled month. The tool does not model daily interest, later-dated lump sums, biweekly payments, or a lender's payoff processing.
Why Even Small Consistent Overpayments Compress Loan Tenor
For each modeled month, interest is calculated on the remaining balance and the payment is applied. The split between interest and principal changes as the balance declines. The calculator keeps the rate and regular payment fixed unless the loan is cleared early.
The estimate treats the monthly extra as part of that month's payment.
The Compounding Effect of Avoiding Future Interest Accrual
When a modeled balance is reduced earlier, later modeled interest is calculated on a smaller amount. The savings shown are a projection based on your inputs, not a guaranteed reduction in the lender's charges.
Configuring Your Accelerated Payoff Plan
For a useful estimate, enter the current amount owed rather than the original amount borrowed, along with your rate and regular monthly payment.
Entering Current Outstanding Balance and Scheduled Note
Use a recent statement or lender account to find the current balance and payment. If the balance has changed since it was reported, your estimate will change too. The regular payment must be greater than the first modeled month's interest for the balance to decline and eventually clear.
Testing Monthly Extra Payments and One-Time Lump Sums
The calculator includes two optional inputs, with an important timing assumption:
- Monthly extra: The same additional amount is included with every monthly payment in the modeled plan.
- One-time lump sum: The amount is applied to the balance before the first modeled interest period. The calculator does not let you select a later date for this payment.
- Both inputs: The model applies the lump sum first, then includes the recurring extra with monthly payments.
Analyzing the Payoff Results
The estimate reports the payoff period, modeled interest, total paid, and any difference in time or interest under the modeled comparison. When a lump sum is entered, the calculator compares the monthly-extra plan with a plan that applies the same lump sum but no recurring extra. The example table also shows the combined plan against the no-extra, no-lump baseline.
Your Accelerated Debt-Free Date vs Contract Maturity
This example uses a $25,000 balance, 8.50% annual rate, $550 regular monthly payment, and November 1, 2026 next due date. Dates are estimates based on counting monthly payments from that date.
| Repayment Scenario | Monthly Payment | Lump Sum | Payoff Time | Calendar Payoff Date | Total Interest Paid | Difference vs. No-Extra, No-Lump Baseline |
|---|---|---|---|---|---|---|
| Contractual Baseline | $550.00 | $0.00 | 56 months | June 1, 2031 | $5,277.59 | Baseline |
| +$150/mo Extra Payment | $700.00 | $0.00 | 42 months | April 1, 2030 | $3,925.19 | Save 14 mos & $1,352.40 |
| $1,000 Lump Sum + $150/mo | $700.00 | $1,000.00 | 40 months | February 1, 2030 | $3,590.92 | Compared with baseline: 16 fewer payments and $1,686.67 less modeled interest |
Compare the Modeled Interest and Payment Counts
With $150 extra each month and no lump sum, this example clears in 42 modeled payments instead of 56 and reduces modeled interest by $1,352.40. Adding the $1,000 upfront lump sum as well brings the modeled total to 40 payments and $3,590.92 in interest. The calculator reports the two effects separately: of the $1,686.67 total saving against the baseline, $1,352.40 (14 of the 16 months) comes from the recurring extra, and the $1,000 lump sum adds 2 months and $334.27 more. The actual payoff and savings depend on your contract, timing, and how the lender handles payments.
Before Sending Extra or Final Payments
This tool estimates a monthly payment path. It does not know your lender's actual balance, payment posting date, fees, or payoff instructions. The estimate assumes the loan carries no prepayment penalty.
Ask Your Lender for a Payoff Quote
Before making a final payment, request a current payoff quote and payment instructions from your lender or servicer. The amount and valid-through period can depend on the contract, interest accrual, fees, and payment processing. Do not use this calculator's estimated total as the payoff amount.
Review Your Contract for Early-Payment Terms
Do not assume every loan has the same early-payment rules or fees. Check your agreement and ask the lender whether any charges or conditions apply to extra payments or early payoff.
Confirm How Extra Payments Are Applied
Ask whether extra payments reduce principal, change your next due date, or are handled another way. Follow the servicer's instructions and check a later statement to confirm how the payment was credited. The estimate assumes the extra reduces the modeled balance as part of each payment.
Consider Other Financial Priorities
Paying extra may reduce modeled interest, but it also uses cash that could serve other needs. Consider your emergency savings, other debts, loan terms, and need for liquidity. The calculator does not compare investment returns or provide personalized financial advice.
To inspect your complete month-by-month repayment breakdown, visit our Amortization Calculator, prioritize multiple debts simultaneously with our Debt Payoff Calculator, or verify contractual monthly installments using our Loan Payment Calculator.
The payoff-amount math is loan-agnostic: a car balance, the payoff on a house mortgage, or a land contract price all follow the same interest accrual from the balance, rate, and payment cadence you enter, with an optional due date pinning the result to a calendar date. What differs between loan types is the accrual basis in the note, so check the quote terms before trusting any single figure.
Last verified: October 2026. Results are computed from the inputs entered and do not reflect live bureau data, creditor balances, or a payoff quote.