Auto Loan Refinance Calculator — Keep vs Refinance
Refinance car loan math in one view: compare finishing your current auto loan against a new rate, term, and closing fees — including interest savings and break-even months.
Current loan & refinance offer
Keep current loan
$514.25/mo
43 months · $3,098.74 interest
Refinance
$448.19/mo
48 months · $2,614.07 interest
Estimated interest savings: $484.67
Monthly payment change: $66.06
Fees break even in ~7 months of payment savings
Refinance estimates only. Your lender may use different payoff quotes, fees, or underwriting rules. Check both lenders' payoff quotes before refinancing.
When refinancing pays off — and when it doesn't
Worth running the numbers
- Your credit score has recovered since you financed. Moving from a subprime APR to a mid-tier one is where the biggest savings live.
- You took the dealer's financing to close the deal and never shopped it against a bank or credit union.
- Rates have dropped since you signed and you still have two years or more left on the loan.
Usually better to keep the loan
- You are in the final stretch. Most interest on an amortized loan is paid early, so there is little left to save.
- You owe more than the car is worth. Many lenders cap a refinance near the vehicle's current value.
- Fees plus a longer term would wipe out the APR savings — the break-even readout above tells you this directly.
Worked examples
Both examples come straight from the calculator above — enter the same numbers and you'll get the same results.
Credit score recovered
$18,500 balance · 42 months left at 11.9% APR → refinance at 6.5% for 42 months, $399 in fees
Payment drops from $540.70 to $504.31 and total interest falls from $4,209.61 to $2,282.11 — about $1,928 saved, with fees breaking even in roughly 11 months.
Keeping the same 42-month term is what protects the savings: the balance keeps amortizing on the original schedule, just at a cheaper rate.
The term-reset trap
$9,000 balance · 18 months left at 7.4% APR → refinance at 6.9% for 60 months, $300 in fees
The payment drops from $529.80 to $183.71, but total interest climbs from $536.44 to $1,722.82 — about $1,186 more over the life of the loan.
A lower APR and a much lower payment can still cost more when 18 remaining months become 60. A cheaper month is not a cheaper loan.
How this is calculated
We compare finishing your current amortization schedule against starting a new loan at the refinanced balance plus fees.
Keep vs refinance
PMT on remaining balance vs new principal at new APR/termBreak-even months = fees ÷ monthly payment savings when savings are positive.
Federal Reserve G.19 · Our methodology →
Common traps
The payoff quote is not your app balance.
Interest accrues daily, so your lender issues a payoff amount that is only valid for about 10–15 days. Refinancing against the number in your banking app leaves a small gap that surprises people at closing.
A longer term can cost more even at a lower APR.
Stretching the remaining months resets amortization from scratch. Compare at your current remaining term first, then decide whether payment relief is worth the extra interest — the second worked example above shows how far apart the two can be.
Financed fees earn interest too.
Rolling fees into the new principal means paying interest on the fee for the whole term. A small fee with a short break-even is fine; a large fee on a small balance rarely is.
Older, high-mileage cars may not qualify.
Many lenders cap refinancing by vehicle age, mileage, and loan-to-value ratio — so approval gets harder exactly when the loan is oldest and the savings window is smallest.
Related calculators
If the comparison says keep your loan, paying extra principal is the other way to cut interest — no fees, no approval, and you can stop any month.
Common questions
Usually when a lower APR or shorter term cuts total interest by more than fees — and you plan to keep the loan past break-even. See our guide on when to refinance a car loan for the decision checklist.