How does the refinance comparison work?
The calculator first rebuilds your current loan. Using the balance, current rate and months remaining, it finds the payment that would retire the balance on schedule and the interest you would still pay by keeping the loan.
It then treats the same balance as a brand-new loan at the new rate and term, computing its payment and total interest. Monthly savings is the old payment minus the new one. Interest saved is the old loan's remaining interest minus the new loan's total interest.
Because the new lender pays off the old loan, the balance carries over unchanged. In reality the payoff amount may be slightly higher because of interest accrued since your last payment, and you may face fees to switch.
Current payment Mc = B × rc(1 + rc)^nc ÷ ((1 + rc)^nc − 1) New payment Mn = B × rn(1 + rn)^nn ÷ ((1 + rn)^nn − 1) Monthly savings = Mc − Mn Interest saved = (Mc × nc − B) − (Mn × nn − B)
- B
- current balance
- rc, rn
- current and new monthly rates (annual ÷ 12)
- nc
- months remaining on the current loan
- nn
- new term in months
Example: refinancing $19,400 from 10.9% to 6.4%
Scenario: A borrower who took a car loan when their credit was weaker owes $19,400 at 10.9% with 44 months left. After their credit improves, they are offered 6.4% for the same 44 months.
- Current payment$19,400 at 10.9% over 44 months = $536.84
- Interest left on current loan$536.84 × 44 − $19,400 = $4,220.96
- New payment$19,400 at 6.4% over 44 months = $495.83
- New total interest$495.83 × 44 − $19,400 = $2,416.52
- Monthly savings$536.84 − $495.83 = $41.01
- Interest saved$4,220.96 − $2,416.52 = $1,804.44
Refinancing cuts the payment by $41.01 a month and saves $1,804.44 in interest before fees.
If switching costs, say, $325 in lender and title fees, the net saving is about $1,479.44.
When is it worth checking a car refinance?
Your credit score has improved
If your score has risen since you took the loan, you may now qualify for a lower rate. Run your current loan against a quote to see the difference.
You took dealer financing without shopping
Dealer-arranged rates are sometimes higher than what a bank or credit union would offer. Comparing a fresh quote shows whether you left money on the table.
You need a lower payment for a while
A longer term can ease a tight budget. The calculator shows exactly how much extra interest that relief costs, so you can decide with eyes open.
Removing or adding a co-borrower
A refinance can change who is on the loan. Check that the new rate and term still make financial sense for the person keeping the loan.
What refinance mistakes cost money?
Judging by the monthly payment alone
A longer term can produce a lower payment even with no rate improvement. Check the interest-saved figure; if it is negative, the refinance costs more overall.
Ignoring fees
Application fees, title transfer and re-registration charges, and any prepayment penalty on the old loan reduce your savings. Subtract them from the interest saved.
Refinancing too late
Had the example borrower waited until 14 months remained, with about $7,027.68 still owed, the same rate drop would save only about $203.79, because most of the interest is already paid.
Letting the balance outrun the car's value
Stretching the term on an older car can leave you owing more than it is worth for longer. Many lenders also limit refinancing by vehicle age, mileage and loan-to-value.
Applying everywhere at once without a plan
Rate shopping is sensible, and scoring models generally treat multiple auto loan inquiries within a short window as one. Keep your applications within a few weeks.
How does the new term change what a refinance saves?
The new rate sets how much you can save; the new term decides how much of that you keep. The table uses the example's $19,400 balance and 6.4% new rate and compares it with the current loan's 44 remaining months at 10.9%.
A 36-month term raises the payment by $56.87 but saves the most interest. At 44 months, the refinance saves both monthly and overall. At 72 months the payment falls by $211.65 a month, yet interest saved shrinks to $207.28, because 28 extra months of interest consume almost all of the lower rate's benefit; a few hundred dollars of fees would turn it negative. The longer term also keeps you paying on a car that keeps aging.
| New term | New payment | Monthly savings | New total interest | Interest saved |
|---|---|---|---|---|
| 36 months | $593.71 | -$56.87 | $1,973.56 | $2,247.40 |
| 44 months | $495.83 | $41.01 | $2,416.52 | $1,804.44 |
| 48 months | $459.18 | $77.66 | $2,640.64 | $1,580.32 |
| 60 months | $378.68 | $158.16 | $3,320.80 | $900.16 |
| 72 months | $325.19 | $211.65 | $4,013.68 | $207.28 |
Terms used on this page
- Refinancing
- Refinancing replaces an existing loan with a new one, usually to get a lower interest rate, a different term or a lower payment. The new lender pays off the old loan, and you repay the new one. It saves money when the rate drop outweighs any fees, but stretching the term can raise total interest.
- Loan-to-Value Ratio (LTV)
- Loan-to-value ratio compares the amount you borrow with the value of the asset securing the loan, shown as a percentage. A $20,000 loan on a $25,000 car is 80% LTV. Lenders use LTV to judge risk: a lower ratio usually brings easier approval and better rates, while an LTV above 100% means you owe more than the asset is worth.
- Prepayment Penalty
- A prepayment penalty is a fee some lenders charge if you pay off a loan early or pay down a large part of it ahead of schedule. It compensates the lender for interest it will no longer receive. Many consumer loans have no such penalty, but if yours does, the terms must appear in your loan disclosures.
- Credit Score
- A credit score is a three-digit number that summarizes how risky you look as a borrower, based on the information in your credit reports. Most widely used models run from 300 to 850. Lenders use scores to decide whether to approve you and what rate to charge, so a higher score usually means cheaper credit.
- Loan Term
- The loan term is the length of time you have to repay a loan, usually stated in months for consumer loans. A longer term lowers the monthly payment but increases the total interest you pay, because the balance stays outstanding longer. A shorter term costs more each month and less overall.
Auto Refinance Calculator: common questions
How much can I save by refinancing my car loan?
The savings depend on the rate drop, the balance and how many months remain. In the example above, cutting 4.5 percentage points on a $19,400 balance with 44 months left saves $1,804.44 before fees. A small rate drop on a small, nearly paid-off loan may save little once fees are counted.
Does refinancing a car hurt your credit score?
There is usually a small, temporary dip from the hard inquiry and the new account. Scoring models generally group auto loan inquiries made within a short period, so rate shopping over a few weeks counts much like a single inquiry. On-time payments on the new loan rebuild any lost points over time.
When is the best time to refinance a car loan?
Refinancing tends to pay off most when your credit has improved or market rates have fallen, and you are still early enough in the loan that substantial interest remains. Many lenders also want the car to be under a certain age and mileage. Late in a loan, savings shrink quickly.
Can I refinance a car loan with negative equity?
It can be harder, because lenders look at the loan-to-value ratio and may cap how much they will lend relative to the car's value. Some will refinance with a higher rate or require you to pay down the difference. Paying extra toward principal first can make you eligible. Another option is to keep the current loan and make extra principal payments until the balance falls below the car's value, then refinance.
Are there fees to refinance an auto loan?
Often yes. You may pay a lender application or origination fee, a state title or re-registration fee, and possibly a prepayment penalty on the old loan if the contract allows one. This calculator ignores fees, so subtract them from the interest saved to find your net benefit. On a small balance with few months left, even a modest fee can erase the savings, so get the exact figures from both lenders before applying.
Should I extend my term when I refinance my car?
Only if you need the lower payment and accept the trade-off. Extending the term lowers the payment but adds months of interest, which can erase the benefit of a lower rate. Choosing a term no longer than your remaining months keeps the savings intact. If you do extend, you can still make the old, higher payment voluntarily when your budget allows, which recovers much of the lost savings.
How soon after buying a car can I refinance?
Some lenders let you refinance within a few months, once the title has been transferred and the first payments are recorded. Others set a minimum waiting period. The practical question is whether you can get a meaningfully better rate than you have now. If you financed with negative equity or a large balance relative to the car's value, waiting until you have paid some principal down may help you qualify.
Is a 1% lower rate worth refinancing a car?
It can be on a larger balance with years remaining, but the dollar amount may be modest. On $19,400 over 44 months, dropping from 7.4% to 6.4% saves about $393.80 in interest. Compare that figure with the fees before deciding. The same one-point drop matters more on a larger balance with more months remaining, and less as the loan nears its end.
What is the difference between payoff amount and balance?
The balance on your statement is the principal owed as of the last payment. The payoff amount adds interest that has accrued since then, up to the day the new lender sends the money, plus any fees. It is usually a little higher, and it is the figure the new loan must cover.
Sources
- Auto loans — Consumer Financial Protection Bureau. Accessed October 17, 2026.
- Credit reports and scores — Consumer Financial Protection Bureau. Accessed October 17, 2026.
- Regulation Z (Truth in Lending), 12 CFR Part 1026 — Consumer Financial Protection Bureau. Accessed October 17, 2026.
We cite primary sources: regulators, central-bank data and federal agencies. Worked examples on this page are our own calculations, last checked October 17, 2026. See our methodology.