1
Auto & Vehicle
Auto Loan Refinance Calculator — New Payment, Monthly Savings & Break-Even
See whether refinancing your car actually saves money once fees are in the picture
Refinancing a car loan means replacing your current loan with a new one — ideally at a lower APR (annual percentage rate), a different term, or both. When rates drop or your credit score climbs after a year of on-time payments, a refinance can cut your monthly payment, shrink the total interest you'll pay, or both. But a lower rate isn't automatically a win: stretching the term to lower the payment can actually increase total interest, and small fees can wipe out a thin monthly saving. This calculator does the apples-to-apples comparison so you can see the real outcome before you sign.
The math is the standard amortizing-loan formula, applied to both the old and new loan and then compared. Your monthly payment is:
M = P × r × (1 + r)ⁿ ÷ ((1 + r)ⁿ − 1)
where P is the loan balance, r is the monthly rate (APR ÷ 12 ÷ 100), and n is the number of months. The calculator runs this for your current loan (using your current rate and the months left, or the payment you already know) and again for the new loan (new rate, new term), then reports four things: the new payment, the monthly savings, the total interest difference, and — if there are fees — the break-even point.
Worked example. You owe $24,000 with 48 months left at 7.5% APR, so your current payment is about $580.29/mo and you still owe roughly $3,854 in interest. You refinance to 5.49% over a fresh 48 months with $200 in fees. The new payment is $558.05/mo — a $22.25 monthly saving — and the new loan carries only $2,786 of interest, so you save about $1,068 in interest. After the $200 fee, your break-even is 200 ÷ 22.25 ≈ 9 months, and your net lifetime saving is about $868.
The most common mistake is chasing a lower monthly payment by extending the term. Refinancing a 48-month balance into a new 72-month loan will almost always drop the monthly number — but you may pay more total interest because you're borrowing for longer, even at a lower rate. Always compare the total interest, not just the payment. The second trap is ignoring fees: title transfer, lien re-registration, or prepayment penalties on the old loan can erase a small monthly saving, which is exactly why the break-even line matters.
This calculator gives an informational estimate, not a loan offer or financial advice. Your real rate, fees, and payoff amount depend on the lender and your credit — always confirm the final numbers on your refinance paperwork.
📖 See also: Should You Refinance Your Auto Loan?
Calculator
Fill in the fields and click "Calculate" for instant results.
📰 Formula
• Monthly rate r = APR / 12 / 100 • Monthly payment M = P × r × (1 + r)^n / ((1 + r)^n − 1) • If APR = 0: M = P / n • Current payment from rate: M_old = payment on balance at current rate over months remaining • Total interest (each loan) = (M × n) − balance • Monthly savings = M_old − M_new • Total interest difference = interest_old − interest_new • Break-even months = fees / monthly savings (only if you save each month)
📰 Formula
• Monthly rate r = APR / 12 / 100 • Monthly payment M = P × r × (1 + r)^n / ((1 + r)^n − 1) • If APR = 0: M = P / n • Current payment from rate: M_old = payment on balance at current rate over months remaining • Total interest (each loan) = (M × n) − balance • Monthly savings = M_old − M_new • Total interest difference = interest_old − interest_new • Break-even months = fees / monthly savings (only if you save each month)
🧪 Worked examples
2
Example 2
3
Example 3
4
Example 4
⚠️ Common mistakes
- Chasing a lower payment by extending the term, which can raise total interest.
- Ignoring refinance fees and prepayment penalties when comparing the two loans.
- Entering the APR as a decimal (0.0549) instead of a percent (5.49).
- Comparing the new payment to the original payment instead of the months you have left.
💡 Tips
- Compare total interest across both loans, not just the monthly payment — a longer term can cost more even at a lower rate.
- Watch the break-even line: if you'll sell or pay off the car before then, the fees aren't worth it.
- Keep the same number of months (or fewer) to lock in the rate savings without re-stretching the loan.
Embed this calculator on your site
Copy the code below and paste it into the HTML of your site or blog.
<iframe src="https://www.calcnimbus.com/embed/auto-loan-refinance-calculator" width="100%" height="500" frameborder="0" style="border:1px solid #eee;border-radius:12px"></iframe>
❓ Frequently asked questions
How does an auto loan refinance calculator work?
It runs the standard amortization formula on your current loan and a new loan, then compares them. Enter your balance, current rate (or payment) and months left, plus the new rate, new term, and any fees. It returns the new monthly payment, monthly savings, total interest difference, and your break-even point.
Is refinancing my car loan worth it?
It's usually worth it when the new APR is meaningfully lower, you keep the term the same or shorter, and you'll keep the car past the break-even point. If fees are high or you stretch the term, the savings can shrink or disappear, which is what the break-even line shows.
Will refinancing lower my monthly car payment?
Often yes — either from a lower APR or a longer term. But a longer term lowers the payment while raising total interest. The calculator shows both the new payment and the total interest so you see the full trade-off, not just the smaller monthly number.
What is the break-even point on a refinance?
It's the number of months it takes for your monthly savings to cover the refinance fees. Break-even months = fees ÷ monthly savings. If fees are $200 and you save $22.25 a month, you break even in about 9 months; after that, the savings are yours.
Does refinancing a car hurt my credit?
A refinance triggers a hard inquiry and opens a new account, which can ding your score a few points temporarily. Most people recover within a few months of on-time payments. The interest you save usually outweighs the short-term dip if the numbers work.
How much can I save by refinancing my auto loan?
It depends on the rate drop, your balance, and the term. In the worked example, dropping from 7.5% to 5.49% on a $24,000 balance saves about $22 a month and roughly $1,068 in interest over the loan, minus a $200 fee for a net savings near $868.
Can I refinance a car loan I'm upside down on?
It's harder if you owe more than the car is worth (negative equity), because lenders cap how much they'll finance against the vehicle's value. Some will roll the gap into the new loan, but that raises your balance and interest. The calculator works on whatever balance you enter.
Should I keep the same term or extend it when I refinance?
Keeping the same number of months (or fewer) locks in the rate savings without re-stretching the loan, so you pay less total interest. Extending the term lowers the monthly payment but usually costs more overall — compare the total interest line for both.
What fees come with refinancing an auto loan?
Common ones are a lien-transfer or title re-registration fee, a small state filing fee, and occasionally a prepayment penalty on your old loan. Enter the total in the fees field so the break-even and net-savings numbers account for them.