Car Refinance Calculator

A car refinance calculator compares the auto loan you have with the one that would replace it. Example: a $22,000 balance with 48 months left at 9.5% costs $552.71 a month; refinanced at 6.5% for the same 48 months it costs $521.73, saving $30.98 a month, $1,487 in interest and about $1,337 overall after a $150 fee, with break-even in month 5.

Three sister tools cover the neighboring questions: the Auto Loan Calculator prices a brand-new purchase loan with tax and trade-in, the Refinance Calculator does the same comparison for a mortgage, and the Loan Comparison Calculator lines up any two loan offers side by side. Use this page when you already have a car loan and a refinance quote in hand.

How the auto refinance calculation works

Both loans are priced with the same fixed-rate amortization formula, applied to the balance you still owe:

where B is the remaining balance, r is the monthly rate (APR ÷ 12) and n is the number of monthly payments. For the current loan, n is the months remaining; for the new loan, n is the new term. From the two payments the calculator derives:

• Monthly savings = current payment − new payment.
• Total interest on each loan = payment × n − balance.
• Lifetime savings = current total of payments − new total of payments − fees paid upfront.
• Break-even month = fees ÷ monthly savings, rounded up.

If you choose to roll the fees into the loan, the new balance becomes B + fees and nothing is paid upfront, so the fee cost shows up as a slightly higher payment and more interest instead of a cash outlay.

Worked example: same term, lower rate

Suppose you owe $22,000 on a car loan at 9.5% APR with 48 months left. The amortization formula gives a current payment of $552.71; over 48 months that is $26,530.03 in total payments, of which $4,530.03 is interest still to be paid.

A credit union offers 6.5% for 48 months with a $150 title and lien fee, paid at closing. The new payment is $521.73, total payments $25,042.99 and total interest $3,042.99. The comparison:

• Monthly savings: $552.71 − $521.73 = $30.98.
• Interest saved: $4,530.03 − $3,042.99 = $1,487.04.
• Lifetime savings after the fee: $26,530.03 − $25,042.99 − $150 = $1,337.04.
• Break-even: $150 ÷ $30.98 = 4.84, so the fee is recovered in month 5.

Because the term is unchanged, every dollar of the monthly saving is a real saving. This is the cleanest kind of refinance: the same payoff date, a smaller payment, less interest.

Worked example: the longer-term trap

Now take the same $22,000 loan and the same 6.5% rate, but stretch the new term to 72 months. The payment falls to $369.82, a drop of $182.89 a month, which looks like a huge win. Total payments, however, rise to $26,626.93 with $4,626.93 in interest, more than the $4,530.03 you would pay by simply finishing the current loan. After the $150 fee you end up $246.90 worse off, and you stay in debt for two extra years. The calculator shows a red warning in exactly this case and points out that refinancing for the original 48 months would save $1,337 instead.

A 60-month term sits in between: $430.46 a month (a $122.25 saving), $3,827.32 in interest and $552.72 of lifetime savings. The lower rate still wins, but roughly $784 of the potential savings is given up to the extra 12 months. Whether that trade is worth it depends on how badly you need the cash flow today.

New payment and total interest by rate and term ($22,000 balance)

Each cell shows the monthly payment and, in parentheses, the total interest over the full term. All figures come from the amortization formula on a $22,000 balance with no fees.

Read the table against the current loan's $4,530 of remaining interest: every 36- and 48-month cell beats it, the 60-month column beats it up to about 7.5%, and the 72-month column only wins at 5.5% and 6.0%. Term length moves total interest far more than half a point of rate does.

Monthly savings and interest saved by new rate (48 months remaining)

Holding the $22,000 balance and the 48-month term fixed, this is what each rate reduction from 9.5% is worth:

The relationship is nearly linear: on this loan each full percentage point of APR is worth roughly $10 a month and about $500 in interest over four years. That gives you a quick way to judge a quote before you even open the calculator.

Break-even month by fees and monthly savings

Break-even is simply fees divided by monthly savings, rounded up to the next whole month. The table makes the trade-off visible: modest fees are recovered quickly, but a large fee on a small saving can take years.

Compare the break-even month with two dates: when you expect to sell or trade the car, and when the loan would end anyway. A 34-month break-even on a loan with 36 months left is barely worth the paperwork.

How to use this car refinance calculator

1. Remaining balance: take the principal balance from your latest statement or online account, not the 10-day payoff quote, which includes accrued interest.
2. Current APR: the rate on your loan contract. If the implied payment shown under the inputs does not match your real payment, your loan may include add-ons or a different balance; adjust until it matches.
3. Months remaining: count the payments left. The calculator accepts 1 to 120.
4. New APR: the rate on the refinance quote. Use the APR from the lender's Truth in Lending disclosure, since it already reflects finance charges.
5. New term: pick 36, 48, 60 or 72 months, enter a custom figure, or press the match button to keep your current payoff date.
6. Fees: enter title, lien and lender fees, then choose whether you pay them at closing or roll them into the new balance.

Read the headline monthly savings first, then the break-even and lifetime savings tiles. The side-by-side table shows where the money moves, and the rate-by-term grid tells you how much better or worse a slightly different offer would be.

Who this calculator is for

• Buyers who financed at the dealership with a marked-up rate and now have a lower quote from a bank or credit union.
• Borrowers whose credit has improved since they bought the car and who now qualify for a better tier.
• Anyone who took a high rate in a tight market and wants to check whether today's offer is a real improvement.
• Households that need a lower payment and want to see exactly what a longer term costs them in interest.
• People comparing several refinance offers who need a common yardstick: lifetime savings after fees.

Key terms

• Remaining balance: the principal you still owe, before any interest that has accrued since your last payment.
• APR: the annual percentage rate, the yearly cost of credit including the interest rate and certain finance charges, as disclosed under the federal Truth in Lending Act.
• Term: the number of monthly payments on the loan. Refinancing lets you keep, shorten or extend it.
• Break-even: the month in which accumulated monthly savings first equal the fees you paid to refinance.
• Lifetime savings: the total of all remaining payments on the old loan minus the total of all payments on the new loan minus upfront fees.
• Loan-to-value (LTV): the loan balance divided by the vehicle's value; lenders use it to decide whether they will refinance at all.
• Prepayment penalty: a fee some contracts charge for paying the loan off early, which is what a refinance does to the old loan.

What changes the result the most

• Rate gap: on a $22,000 balance over 48 months, each percentage point is worth about $10 a month and $500 in interest. Small gaps rarely justify fees.
• Months remaining: the more time left, the more interest there is to save. A $12,000 balance with 24 months left at 9.5% carries only $1,223 of remaining interest; refinancing to 6.5% saves $16.42 a month and $394 in total.
• New term: extending the term is the single biggest reason a refinance with a lower rate can still cost more overall.
• Fees and how you pay them: upfront fees set the break-even; rolled-in fees add interest for the whole term.
• Balance size: savings scale with the balance, so the same rate drop is worth twice as much on $44,000 as on $22,000.

Tips for a refinance that actually saves money

• Match the remaining term first. Use the match button and look at the lifetime savings; only then decide whether a longer term is worth its cost.
• Shop several lenders within a short window so the credit inquiries are treated as one, and compare APRs rather than advertised rates.
• Check the old contract for a prepayment penalty and add it to the fees field if there is one.
• Refinance early in the loan when the balance and remaining interest are largest, and skip it in the final year when little interest remains.
• Keep paying the old payment on the new loan if you can. Applying the monthly savings to principal shortens the new loan and captures the rate drop as pure interest savings.

Limitations and assumptions

• The current payment is inferred from balance, APR and months remaining. Loans with financed add-ons, deferred payments or precomputed interest will not match exactly.
• Both loans are assumed to be simple-interest, fixed-rate loans with level monthly payments and no prepayment penalty on the old loan.
• The calculator does not know your vehicle's value, so it cannot tell you whether a lender will approve the loan-to-value ratio.
• The break-even ignores the timing of payments within the month and the small amount of interest that accrues between the old loan's payoff and the new loan's first payment.
• Rate eligibility depends on credit score, vehicle age and mileage, and lender policy; the calculator only prices the rate you enter.

Related calculators

This page answers "is this refinance quote worth it?" For neighboring questions, a sister tool fits better: the Auto Loan Calculator when you are buying rather than refinancing, the Car Payment Calculator for a quick payment from amount, rate and term, the Loan Payoff Calculator to see how extra payments shorten your current loan without refinancing, the APR Calculator to turn a rate plus fees into a true APR, and the Cumulative Interest Calculator to check how much interest you have already paid on the old loan.

Sources

• Consumer Financial Protection Bureau (CFPB) - Auto loans: shopping, comparing and managing a car loan.
• Consumer Financial Protection Bureau (CFPB) - What is the difference between a loan's interest rate and its APR?
• Consumer Financial Protection Bureau (CFPB) - What is a prepayment penalty?
• Truth in Lending Act, Regulation Z (12 CFR Part 1026) - required APR and finance charge disclosures on consumer credit.