Loans & borrowing · Free calculator

Lump-Sum Loan Payoff Calculator

Estimate the payoff date and net interest savings from one extra principal payment, including an early-payment charge.

01 / Set your scenario

Your inputs

02 / Review your estimate

Estimated results

Change the inputs to explore a different scenario.

Method and limitations

One-time principal is paid immediately after the selected regular installment. Compare remaining interest with the original schedule, subtract the entered charge, and keep regular installments unchanged.

Fixed rates, monthly periods and no additional charges unless entered. Real lender methods, daily accrual, payment allocation and rounding can differ. Confirm all terms in the actual disclosure. Inputs stay in this browser; this tool does not submit them.

US dollars. Defaults are hypothetical, not current lender offers.

Adjust the inputs, then select Calculate to review your scenario.

Method, assumptions and result checks

What this tool covers: Estimate the payoff date and net interest savings from one extra principal payment, including an early-payment charge.

A standard monthly amortizing-loan payment is P × r ÷ [1 − (1 + r)⁻ⁿ], where P is principal, r is the annual note rate divided by 1,200 and n is the number of monthly payments. At zero interest, payment is P ÷ n. Fees, extra payments and rate changes depend on the specific options and method described on this page.

Review the calculator’s worked examples, formulas, timing and exclusions in the sections below. Input units and payment frequency matter. A displayed APR is not necessarily the interest rate used by the model. Tax, investment, daily-interest and specialist loan models have different rules.

Interface and accessibility reviewed November 8, 2026. This is not a certification of current rates, tax tables or every financial statement. Verify important results against actual documents.

Monthly loan formulas and worked examples · Build questions for your lender

Estimate the payoff date and net interest savings from one extra principal payment, including an early-payment charge.

Learn more about this calculation

Review these related guides before comparing estimates with actual lender terms.

How to use this calculator & related guidance

Keep timing and early-payment charges visible

The one-time amount is applied after the selected regular installment. Compare different months and inspect the changed balance. An early-payment charge is treated as cash paid separately, not added to principal or charged again within installments.

Use the result in three steps

Copy the amounts, contract rates and dates from the actual offer. The presets are invented examples.
Save a baseline, change one assumption and compare results. Inspect the full schedule where available.
Use Verify to check the software arithmetic, then export the current scenario. Self-checks do not verify your contract or eligibility.

Key takeaways before using this estimate

If the regular installment already clears principal, there is no remaining balance to receive the extra payment. Choose an earlier month. The tool will flag that scenario rather than claim savings from an unused payment.
No. The displayed saving is modeled interest avoided minus the charge entered. It does not value cash retained for emergencies, investment returns or the cost of replacement borrowing.
CSV and PDF use the last valid scenario. Display currency relabels amounts without converting exchange rates.

Frequently asked questions

Can I pay the lump sum in the final month?

If the regular installment already clears principal, there is no remaining balance to receive the extra payment. Choose an earlier month. The tool will flag that scenario rather than claim savings from an unused payment.

Does the saving include my cash reserve?

No. The displayed saving is modeled interest avoided minus the charge entered. It does not value cash retained for emergencies, investment returns or the cost of replacement borrowing.

Published by Saad Faisal · last updated November 1, 2026. Results are estimates for planning, not financial advice.

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