Car Loan Refinance Calculator
Compare your current auto loan against a refinance offer to see your real monthly and lifetime savings
Refinance Calculator
Enter your current loan and the new offer to compare
Current Auto Loan
Your 10-day loan payoff amount, not the original loan amount.
New Loan Offer
Defaults to your remaining term — change it to see how a shorter or longer term affects total cost.
Title transfer, processing, or application fees, if any.
Total Interest: Current vs. Refinanced
Current Loan
Refinanced Loan
Car Loan Refinance Calculator: Is Refinancing Your Auto Loan Worth It?
Refinancing an auto loan means replacing your current loan with a new one — ideally at a lower rate, a different term, or both. Our free car loan refinance calculator at MyCalculator.us compares your current loan against a new offer side by side, so you can see the real monthly and lifetime cost difference before you apply.
What Is a Car Loan Refinance Calculator?
A car loan refinance calculator takes your current loan's payoff balance, rate, and remaining term, plus the rate and term of a new offer, and works out your new monthly payment, your total interest under each loan, and how long it takes any refinance fees to pay for themselves. Unlike a general loan calculator, it's built specifically for the "should I switch" decision — not just "what would a new loan cost."[1]
How the Calculation Works
Both your current loan and the refinance offer use the same standard amortization formula, applied to each loan's own balance, rate, and term:
M = B × [r(1+r)ⁿ] / [(1+r)ⁿ − 1]
Where:
- M = Monthly payment
- B = Loan balance (current payoff amount for both scenarios)
- r = Monthly interest rate (annual rate ÷ 12)
- n = Number of remaining payments
Most auto loans are simple interest loans, meaning interest accrues daily on your outstanding balance rather than being pre-calculated for the full term up front — so paying even a little extra, or refinancing to a lower rate, reduces the interest that accrues on every remaining payment.[2] The calculator subtracts any refinance fees from your total interest savings to show a true net figure, and divides those fees by your monthly payment difference to estimate your break-even point.
A Real Example
Take an $18,000 payoff balance at 9.5% with 4 years remaining — a $452.22 monthly payment and $3,706.39 in remaining interest. Two refinance offers at 6.5% look very different depending on the term:
| Current Loan | Refi, Same Term (4 yrs) | Refi, Extended Term (6 yrs) | |
|---|---|---|---|
| Rate | 9.5% | 6.5% | 6.5% |
| Monthly Payment | $452.22 | $426.87 | $302.58 |
| Total Interest | $3,706.39 | $2,489.72 | $3,785.67 |
| vs. Current Loan | — | Saves $1,216.67 | Costs $79.28 more |
Keeping the same 4-year term at the lower rate saves $1,216.67 in interest, and with a $150 refinance fee, pays for itself in about 5.9 months. Stretching to 6 years drops the payment by nearly $150/month — genuinely useful if cash flow is tight — but ends up costing $79.28 more in total interest than just keeping the current loan, because 24 extra months of interest outweighs the lower rate. Neither choice is "wrong," but only a side-by-side calculation makes the trade-off visible.
When Refinancing Usually Makes Sense
- Your credit score has improved since you took out the original loan — even a 1-2 tier jump can unlock a meaningfully lower rate.
- Market rates have dropped since you financed, independent of your own credit changes.
- You want to keep the same term and simply lower your rate — this is the cleanest way to save money without extending how long you're in debt.
- You need short-term breathing room and are knowingly trading a longer term for a lower payment, understanding the total-interest trade-off shown above.
Things to Check Before You Refinance
- Negative equity. If you owe more than the car is worth, most lenders won't refinance the loan as-is, or will require rolling the negative equity into the new loan — which increases what you're borrowing.
- Prepayment penalties. Check your current loan agreement for early-payoff fees before switching.
- Title and lien transfer fees. Some states charge title fees when a new lender takes over as lienholder — factor these into the "Refinance Fees" field above.
- Add-on products. GAP insurance or extended warranties bundled into your current loan may not automatically transfer to the new one — confirm with your current lender.
- Minimum loan age and balance. Many lenders require your current loan to be a few months old and above a minimum payoff balance before they'll refinance it.
- Compare total cost, not just the monthly payment. A lower payment alone doesn't tell you whether a deal is actually cheaper — total interest over the full term does.[3]
This calculator provides estimates for planning purposes only and isn't financial advice — actual offers depend on your credit profile, lender, state fees, and the vehicle itself.
Frequently Asked Questions
What is a car loan refinance calculator?
A car loan refinance calculator compares your current auto loan against a new refinance offer, showing your new monthly payment, total interest under each loan, net savings after fees, and how long it takes to break even on any refinance costs.
Does refinancing always save money?
No. A lower rate at the same or shorter term almost always saves money, but a lower rate combined with a longer term can end up costing more in total interest even though the monthly payment drops. Always compare total interest, not just the monthly payment.
Can I refinance if I owe more than my car is worth?
It's difficult. Most lenders won't refinance a loan with significant negative equity as-is, and if they do, the shortfall is typically rolled into the new loan, increasing what you owe. Getting closer to being right-side-up first generally leads to better refinance terms.
How long should I wait before refinancing a car loan?
There's no universal rule, but many lenders require the current loan to be at least a few months old before they'll refinance it. If your credit is still recovering, waiting a few months to improve your score before applying often results in a meaningfully better rate.
Will refinancing hurt my credit score?
Applying triggers a hard credit inquiry, which can cause a small, temporary dip in your score. Rate-shopping for auto loans within a short window (typically 14-45 days, depending on the scoring model) is usually treated as a single inquiry rather than several separate ones.