Car Refinance Calculator: Compare Old vs New Payments
Enter your remaining car loan balance, compare the old APR with a new refinance offer, then see the new payment, monthly savings, the break-even point on refinance costs, and total net savings. Includes a term-trap mode showing when a lighter payment actually inflates total interest.
Educational estimate — not financial advice. The figures on this page are computed from your input using the standard amortization formula. Actual lender fees, taxes, and terms may differ. Refinance decisions are best discussed with a licensed financial advisor.
Refinance Comparator
Educational estimate — not financial advice. The results above use the standard amortization formula on the numbers you entered and exclude taxes, insurance, and other lender fees.
Cumulative cost over time
Refinance Break-Even Calculator
Break-even = total refinance cost divided by monthly payment savings. The refinance only starts truly saving money after this month passes.
The Term-Extension Trap
Lowering the payment by extending the term almost always raises total interest. This table is honest: compare payment vs total interest for each term option at the same new APR.
| Term | Payment / mo | Total interest | Interest diff vs 36 mo |
|---|
Anchor example: a 48-month term gives a $418.62 monthly payment, but total interest of $2,093.59 — up $526.65 versus $1,566.94 total interest for the 36-month term at the same 5.5% APR.
Verified example, step by step
Remaining balance $18,000, remaining term 36 months, old APR 9%:
- Old payment = $572.40 per month (standard amortization formula).
- A refinance offer at 5.5% APR + $300 in fees gives a new payment of $543.53 per month.
- Monthly savings = $572.40 − $543.53 = $28.87.
- Break-even = $300 ÷ $28.87 = 10.4 months — from month 11 on, the savings are yours.
- Old total interest $2,606.23 vs new total interest $1,566.94 + $300 fees = $1,866.94.
- Net savings = $2,606.23 − $1,866.94 = $739.28.
All figures above were independently recomputed before publishing.
How the calculation works
Monthly payment uses the standard amortization formula: PMT = P × r(1+r)^n / ((1+r)^n − 1), with P the remaining principal, r = APR ÷ 12 ÷ 100, and n the number of months. Total interest = payment × n − P. Break-even = refinance cost ÷ monthly savings. Net savings = old total interest − (new total interest + refinance cost). All computation runs 100% in your browser; no data is sent anywhere.
Frequently asked questions
Is refinancing a car worth it?
It can be, or not. It depends on three numbers: the old-vs-new APR spread, the remaining term, and total refinance costs. Verified example: a remaining balance of $18,000 with 36 months left at 9% APR has a $572.40 monthly payment. Refinancing to 5.5% APR with $300 in fees lowers the payment to $543.53, saving $28.87 per month. Old total interest of $2,606.23 vs new total interest of $1,566.94 plus $300 in fees gives net savings of $739.28. Refinancing is worth considering when net savings are positive and break-even is reached before the remaining term runs out.
How do you calculate a car refinance break-even?
Divide total refinance cost by monthly payment savings. Example: $300 in costs divided by $28.87 monthly savings gives a 10.4-month break-even. That means from month 11 on you truly enjoy the savings. If break-even is longer than the loan's remaining term, refinancing loses money because the costs never pay back before the loan ends.
Is extending the term when refinancing a trap?
Often yes. Example: refinancing a remaining $18,000 balance to 5.5% APR over 48 months gives a $418.62 monthly payment, looking much lighter than $543.53 over 36 months. But total interest over 48 months is $2,093.59, up $526.65 versus $1,566.94 total interest over 36 months. The payment drops, total cost rises. Always compare total cost, not just the payment.
What fees come up when refinancing a car?
Typically an origination or application fee from the new lender, title transfer and new lien recording fees, and possibly a prepayment penalty on the old loan. Enter all of these in the refinance cost field on the Comparator tab so break-even and net savings are computed honestly.
When is the right time to refinance a car?
Generally when your credit score has risen since the original loan, when market rates have fallen below your old loan's APR, or when the remaining term is still long enough for break-even to be reached. If only a few months remain, the savings usually do not cover refinance costs.
Does this calculator handle cash-out refinance?
No. This calculator only compares an existing auto loan with a replacement refinance loan for the same remaining principal. It is not a cash-out refinance calculator and does not compute drawing extra funds from vehicle equity.
Does refinancing a car affect my credit score?
A refinance application generally triggers a hard inquiry that can lower your score slightly in the short term, and the closed old loan changes your accounts' average age. The exact impact differs per person. This calculator only computes payment and cost figures, not credit impact.
What formula is used to compute the payment?
The standard amortization formula: payment = P x r(1+r)^n / ((1+r)^n - 1), with P the remaining principal, r = APR / 12 / 100, and n the number of months. Total interest = payment x n - P. Break-even = refinance cost / monthly savings. Net savings = old total interest - (new total interest + refinance cost). Every mode on this page uses the same formula, which you can re-verify with any financial calculator.
Also searched as: car refinance calculator, refinance car loan calculator, auto refinance calculator, auto loan refinance calculator, car loan refinance calculator, refinance my car calculator, is it worth refinancing my car, car refinance break even calculator, auto refinance break even, refinance car loan break even point, lower car payment refinance calculator, car refinance savings calculator.