Loan Payoff Calculator
The short answer: extra payments attack the balance, and a smaller balance means less interest every single month after. Enter your balance, APR, and current payment, add an extra amount, and this tool simulates the loan month by month — showing both payoff dates, the exact interest each way, and what the extra money actually buys you.
The other lever: a lower rate
Extra payments cut interest by shrinking the balance; refinancing cuts it by shrinking the rate. Sometimes the refinance wins — run both. myAutoloan and LendingTree refinance offers (via CJ) are the planned partners for this slot.
How this is calculated
No closed-form shortcut — the tool simulates your loan the way the lender's system does: each month, interest is balance × (APR ÷ 12); the rest of the payment reduces the balance; the loan ends with one smaller final payment when the balance runs out. Verified against the closed-form solution: $10,000 at 12% with a $222.45 payment ends in exactly 60 months with about $3,347 of interest, and adding $100 a month ends it in 38 months with about $2,031 of interest — a saving of roughly $1,316. This calculator reproduces both.
Assumptions, stated: the payment and rate never change, extra payments apply fully to principal, and no new charges are added. If your lender applies extra money differently, your real numbers will differ slightly — the statement is the referee. Considering a rate change instead? The refinance calculator runs that side.
Frequently asked questions
How does paying extra on a car loan save interest?
Interest is charged on the balance each month. Every extra dollar paid goes to principal (when applied correctly), so next month's interest is computed on a smaller balance — and that compounds month after month. The savings are real but back-loaded in effect: the earlier the extra payments start, the more they save.
Should I tell my lender the extra is for principal?
Yes. Some servicers apply extra money to future payments instead of principal unless instructed otherwise — which just moves your due date without cutting interest the same way. Mark extra amounts "apply to principal" and confirm on your statement that the balance fell by the full extra amount.
Is paying off a car loan early always smart?
Not automatically. At a low APR, extra cash may do more in an emergency fund or against higher-rate debt. At typical used-car APRs (9%+), though, extra payments earn a guaranteed return equal to the rate — very hard to beat risk-free. This calculator shows the guaranteed part; the comparison is yours.
Do car loans have prepayment penalties?
Most modern auto loans don't, but some do — check your contract for a prepayment-penalty clause before making large extra payments. If one exists, weigh the penalty against the interest saved above.