Auto Loan Payoff Calculator
See exactly how much time and interest an extra monthly payment saves on your car loan — enter your loan details and an extra amount to compare.
How extra payments shorten a car loan
Each extra dollar paid reduces principal immediately, which lowers every future month's interest charge
A car loan charges interest on whatever principal balance remains each month. Your scheduled payment is fixed, but an extra payment goes straight to principal (assuming your lender applies it that way), which means every remaining month's interest is calculated on a smaller balance — the loan pays itself off faster than the original schedule, and you owe less interest overall.
Standard payment: $586.98/month, paid off in 60 months, total interest $5,219.
With $100 extra every month: paid off in 50 months (10 months early) — total interest drops to $4,323, saving $896.
Same $30,000 loan and 6.5% APR, but a 72-month term instead of 60. Standard payment: $504.37/month, total interest over the full term: $6,315.
With the same $100 extra/month: paid off in about 58 months (14 months early) — total interest drops to roughly $5,054, saving about $1,261. The identical $100 extra payment saves more here than on the 60-month loan, because a longer original term carries substantially more total interest for the extra payments to cut into.
How loan term length changes total interest ($30,000 at 6.5%)
| Term | Monthly payment | Total interest (no extra payments) |
|---|---|---|
| 36 months | $919.66 | $3,108 |
| 48 months | $711.32 | $4,143 |
| 60 months | $586.98 | $5,219 |
| 72 months | $504.37 | $6,315 |
Common mistakes when modeling extra auto loan payments
- Assuming an extra payment shortens the loan by the same number of months every time. Because extra payments compound (each one reduces future interest too), the time saved isn't linear with the extra amount.
- Not confirming the payment applies to principal. Some servicers default to applying extra amounts toward the next scheduled payment instead — always specify "apply to principal" if given the option.
- Ignoring a prepayment penalty clause. Rare on mainstream auto loans, but worth checking your contract before making large extra payments.
Frequently asked questions
How much do extra payments save on a car loan?
It depends on rate and term, but on a $30,000 loan at 6.5% over 60 months, an extra $100/month saves about $896 in interest and finishes 10 months early.
Does an extra payment go entirely toward principal?
Usually, but confirm with your lender — some require you to specify "apply to principal" for extra payments.
Is there a penalty for paying off a car loan early?
Most auto loans don't have one, but some subprime loans do — check your agreement.
Should I pay extra on my car loan or invest the money instead?
If your loan rate is higher than your expected investment return, paying down the loan is the better move mathematically.
Does loan term length affect how much extra payments save?
Yes — longer terms carry more total interest, so the same extra monthly amount saves more on a 72-month loan than a 60-month loan.
Should I choose a 72-month loan for the lower payment?
Generally not recommended — it costs more total interest and keeps you owing more than the car's worth for longer.
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Note: Simplified estimate assuming a fixed-rate loan and extra payments applied fully to principal each month. Not financial advice. Last reviewed: September 2026.