Loan Payoff Calculator

Balance, APR, and what you pay each month — get the payoff date and total interest, then see what adding even a small extra payment saves.

Free — no signup Runs in your browser Pairs with the Promissory Note
Worked example

$12,000 at 9%, $300 a month — then $100 extra

Example: $12,000 balance · 9% APR · $300/month

Paying $300 a month, the loan takes 48 months to clear and costs $2,321 in interest. Add $100 a month and the picture changes:

At $300/mo = paid off in 48 months, interest $2,320.65
At $400/mo = paid off in 35 months, interest $1,645.32
Extra $100 saves = 13 months and $675.33

Extra payments hit hardest early, when the balance — and therefore the monthly interest — is largest. If you’re renegotiating a private loan to a new payment, the revised schedule belongs in an updated promissory note, not a text thread.

FAQ

Loan payoff questions

It simulates the loan month by month: each month the balance accrues one month of interest (balance × APR ÷ 12), your payment is subtracted, and the loop repeats until the balance hits zero. That’s exactly how an amortizing loan behaves, so the month count and interest total match what you’d actually pay.
Every extra dollar goes 100% to principal, and principal you remove today stops generating interest every month for the rest of the loan. That’s why $100 extra on the example loan saves $675 — the savings compound in your favor.
Then the balance grows instead of shrinking — called negative amortization — and the loan never pays off. The calculator flags this instead of showing a misleading date. The fix is a higher payment or a renegotiated rate.
Not automatically — some lenders apply extra amounts to next month’s payment (prepaying interest) unless you direct them to principal. Check how your lender handles it; on private loans, write the application-of-payments rule into the note.

This calculator provides general estimates for planning purposes and is not legal, tax, or financial advice. Assumes payments apply to interest first, then principal, with no prepayment penalty.

You can see the finish line.
Put the plan on paper.

Changing the payment on a private loan? BizDocs writes an updated promissory note with the new schedule, so both sides are protected.

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