An auto loan refinance calculator compares your current vehicle loan with a proposed replacement loan. Enter the existing balance, APR, and months left, then the new APR, term, and fee, and the tool estimates the payment, interest, and full-term cost difference. It does not assess vehicle eligibility, negative equity, title requirements, or lender approval.
A lower payment can improve monthly cash flow without reducing what you pay over the full term. Compare both results before deciding whether an offer fits your needs. This calculator is an estimate, not a lender quote or approval decision.
Refinancing pays off the existing auto loan, so check whether its contract includes a prepayment penalty and compare written offers. The CFPB's auto-loan guidance explains what to review before paying off or refinancing a loan early.
What to enter
- Current balance: The remaining principal, not the vehicle's original purchase price.
- Current APR and months left: The calculator uses these with the balance to estimate the current monthly payment and remaining payment total. It does not ask for your actual payment amount.
- New APR and term: Enter the proposed rate and choose a 12-, 24-, 36-, 48-, or 60-month term.
- Refinance fee: Enter the fee you want included in the comparison. The calculator adds it to the new loan balance and models it as financed.
How both loans are modeled
The calculator estimates each loan as a fixed-rate, monthly amortizing loan. It assumes the current balance is repaid over the remaining term at the entered current APR; actual lender statements can differ because of payment dates, accrued interest, fees, or other contract terms.
How to compare the results
The full-term comparison
The modeled current loan and the refinance scenario each have an estimated monthly payment and total of future payments. The new-loan total includes the entered fee because the tool adds that fee to the amount financed. The difference over the full term compares those estimated totals; it is not an official payoff statement and does not include costs you do not enter.
Reading a payoff quote before you refinance
The number that matters first is not this calculator's estimate but the payoff quote your current lender issues, because refinancing pays that exact amount, not the balance shown on your last statement. A payoff figure typically exceeds the current principal: interest accrues daily, so the quote adds per-diem interest from the last payment to the expected payoff date. Quotes also usually carry a good-through date; pay after it and the amount moves again, which is why the payoff should be requested close to the day the new loan funds. Confirm how the new lender handles the gap between the quoted payoff and the loan it is giving you, and whether the existing contract charges anything for paying off early.
Worked example: lower payment versus lower total cost
These estimates use a $20,000 current balance, 9.50% current APR, 36 months remaining, and a $150 refinance fee added to the new balance. Both refinance cases use a 5.50% APR but different terms.
| Comparison | Current loan estimate | 36-month refinance | 60-month refinance |
|---|---|---|---|
| Modeled principal | $20,000.00 | $20,150.00 | $20,150.00 |
| APR | 9.50% | 5.50% | 5.50% |
| Term | 36 months remaining | 36 months | 60 months |
| Estimated monthly payment | $640.66 | $608.45 | $384.89 |
| Monthly payment difference | n/a | $32.21 lower | $255.77 lower |
| Modeled interest | $3,063.72 | $1,754.13 | $2,943.28 |
| Total future payments | $23,063.72 | $21,904.13 | $23,093.28 |
| Difference from current-loan total | n/a | $1,159.59 lower | $29.56 higher |
| Fee-payback estimate* | n/a | 5 months | 1 month |
About the fee-payback estimate
*The fee-payback estimate is the entered fee divided by the monthly payment reduction, rounded up to a whole month. The calculator finances the fee in the new balance but uses the fee amount in this simple estimate, so it is not an exact cash-flow break-even or the same as net savings over the full term. In the 60-month example, the fee-payback estimate is one month even though the modeled full-term total is $29.56 higher than the current-loan total.
Why a longer term can cost more
Extending the example from 36 to 60 months reduces the estimated payment by $255.77 per month, but the new-loan total is $29.56 higher. The lower monthly payment and lower APR do not by themselves show that refinancing costs less overall. Compare the total payments across the full remaining and new terms.
When refinancing makes no sense
These are heuristics from the model's arithmetic, not rules. First, a small remaining balance: the less principal is left, the less interest there is to remove — the benchmark loan above carries $3,063.72 of interest over its 36 remaining months, and that is the ceiling on what any refinance of it can save. Second, few months left: on the same loan with 6 months to go, the remaining interest is $557.80, so a $150 fee would consume roughly a quarter of the maximum possible saving before the new rate did anything. Third, rolled-in negative equity: if the refinance exists to wrap a gap between the balance and the vehicle's value into a longer term, the model cannot price that risk, and the new loan starts upside down on a slower payoff path.
Negative equity and lender checks beyond the model
The calculator does not assess the vehicle's value, depreciation, or loan-to-value ratio, so it cannot tell you whether you have negative equity or whether a lender will approve the refinance. Ask lenders how they would handle any gap between the balance and the vehicle's value.
What this estimate does not include
The model does not evaluate lender eligibility, credit-score requirements or effects, title procedures, taxes, insurance, vehicle age or mileage, or negative equity. Actual fees and payment terms vary. Confirm the refinance offer, fee treatment, payoff amount, and payment schedule with the relevant lenders before making a decision.
For related estimates, use the Auto Loan Calculator to model vehicle financing, the Car Loan Payoff Calculator to estimate an accelerated payoff, or the Loan Payment Calculator for a general installment payment.
Last verified: October 2026. Calculator figures are outputs for the inputs entered; they are not live quotes, current rates, or an offer.