Auto Finance

Auto Loan Calculator

Break down your car payment by principal, interest, and total cost. See exactly what the dealer's financing really costs.

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Monthly car payment with trade-in & fees

Vehicle Price ($)

Down Payment ($)

Trade-In Value ($)

Sales Tax (%)

Interest Rate (%)

Loan Term

Fees & Other Costs ($)

Extra Monthly Payment ($) optional

Est. Annual Depreciation (%) typ 15–20%

Auto Loan Guide

3 questions

What is a good interest rate for a car loan?

In 2026, average auto loan rates range from 5%–8% for new cars with good credit, and 7%–14% for used cars. Excellent credit (750+) can qualify for rates as low as 3%–5%. Credit unions typically offer lower rates than dealerships.

Should I choose a shorter or longer loan term?

Shorter terms mean higher monthly payments but significantly less total interest. A 36-month vs 72-month loan on $30,000 at 6.5% saves over $3,000 in interest. Longer terms risk being "underwater" — owing more than the car is worth.

How does a trade-in affect my loan?

Your trade-in value is applied as a credit toward the purchase price, reducing the amount you need to finance. This directly lowers your monthly payment and total interest paid. Always get multiple trade-in quotes before visiting a dealer.

Finance Guide

Auto Loan Calculator Guide: Payment, APR, Trade-Ins & Total Cost

A practical guide to using an auto loan calculator to compute monthly payments, factor in trade-in equity and sales tax, decode APR, and avoid the most common car financing traps.

Written by Calculixy Editorial Team · 20 years in financial servicesReviewed by a licensed automotive finance professionalUpdated: May 2026

From the Underwriting Desk

The car-loan industry runs on confusion. Dealers negotiate the monthly payment, not the price. They roll fees into the loan so you don't see them. They stretch terms to 72 and 84 months so the payment looks affordable while the total cost climbs by thousands. An auto loan calculator is your defense — it converts every move the finance manager makes into a number you can verify before you sign anything.

What this calculator does

The Auto Loan Calculator estimates your monthly car payment by combining the vehicle price, sales tax, fees, down payment, and trade-in equity into the actual financed amount — then applying the standard amortization formula. It reports the monthly payment, total interest paid, and total cost of the vehicle including financing.

The critical word here is "financed amount." Calculators that just take a sticker price and a rate miss the moves a dealer makes on the back end. Sales tax in most states is calculated on the post-trade-in price, fees vary by region and dealer, and negative equity from your current car loan can roll silently into the new loan. The calculator's job is to surface all of it.

When to use this calculator

Before walking into a dealership, to set a maximum payment ceiling you won't exceed
To compare a 48-month vs. 60-month vs. 72-month loan on the same car
To check whether a manufacturer's 0% APR offer actually beats taking the rebate and financing elsewhere
To estimate whether a trade-in offer reflects fair equity or rolls negative equity into the new loan
To verify a payment quoted by a dealer matches the rate and term being offered
To stress-test affordability against your total monthly debt obligations

The auto loan payment formula

Every fixed-rate auto loan uses the same amortization formula as any other loan:

M = P × [r(1 + r)ⁿ] / [(1 + r)ⁿ − 1]

Variable definitions

M = Monthly payment
P = Financed amount (vehicle price + tax + fees − down payment − trade-in equity)
r = Monthly interest rate (annual APR ÷ 12)
n = Total number of payments (term in months)

The math is identical to a personal loan or a mortgage. The complexity is in the inputs, not the formula.

Calculating the real financed amount

This is where most online auto loan calculators fall short. The "P" in the formula isn't the sticker price — it's everything you're actually borrowing:

Financed Amount = Vehicle Price + Sales Tax + Fees − Down Payment − Trade-In Equity Where: Trade-In Equity = Trade-In Value − Existing Loan Balance on Trade-In (If existing balance exceeds trade value, equity is negative)

Negative equity warning: If you owe more on your current car than it's worth, rolling that gap into a new loan means you're starting the new loan upside-down. Many dealers will offer to do exactly this — be aware that you'll likely owe more than the new car is worth for the first half of the loan.

Step-by-step example

You're buying a $35,000 vehicle. Sales tax is 6.5% in your state, dealer fees are $700, you're putting $3,000 down, and your trade-in is worth $8,000 with $5,500 still owed on its loan. The loan is for 60 months at 7.5% APR.

Calculate the financed amount:

Sales tax base (after trade-in in most states): $35,000 − $8,000 = $27,000
Sales tax: $27,000 × 0.065 = $1,755
Trade-in equity: $8,000 − $5,500 = $2,500 positive
Financed amount: $35,000 + $1,755 + $700 − $3,000 − $2,500 = $31,955

Calculate the monthly payment:

P = $31,955
r = 0.075 ÷ 12 = 0.00625
n = 60

M = 31,955 × [0.00625 × (1.00625)^60] / [(1.00625)^60 − 1] M ≈ $640 per month

Over 60 months you pay back $38,400. Total interest is approximately $6,445. Combined with the $3,000 down payment, the total cost of the car is about $41,445 — $6,445 above the cash price, plus tax and fees.

APR vs. interest rate (and what dealers play with)

Interest rate

The percentage charged on the principal balance month to month.

APR (Annual Percentage Rate)

The interest rate plus any loan fees, discount points, or financing charges built into the loan — expressed as an annualized percentage. APR is the only fair comparison number between auto loan offers.

Dealer financing tricks to watch for

"Buy rate" markup. The interest rate a lender approves you for is the "buy rate." Dealers can mark it up before quoting you. A 6% buy rate may be quoted as 7.5% with the spread going to the dealership as profit. Bring a pre-approval from your bank or credit union as leverage.
Payment packing. The "monthly payment" quoted at the desk may bundle extended warranties, gap insurance, and dealer add-ons. Always ask for the breakdown.
Stretching the term. "We can get the payment down to $X." Yes — by extending from 60 to 84 months. The payment drops; the total interest jumps by thousands.
"Cash back or low APR" tradeoff. Manufacturer incentives often force a choice between a rebate and a promotional rate. Math out both: sometimes the cash and a third-party loan beat the 0% factory financing.

Always negotiate price first, then payment. Dealers prefer to negotiate the monthly payment because it lets them adjust term and rate to hide the true cost. Settle on the vehicle price separately before discussing financing.

How auto loan amortization actually works

In the first year of a 60-month auto loan at 7.5%, roughly $185 of each $640 payment goes to interest — about 29% of the payment. By year 4, that interest portion drops to about 5% of each payment. Most of your early payments are servicing the loan, not building equity in the car.

This is part of why being upside-down is so common in the first half of an auto loan. Cars depreciate fast (most lose 20% of value in the first year and 60% by year five), while loan principal pays down slowly. Without a substantial down payment or a short loan term, the loan balance can exceed the car's value for the first 24–36 months on a 60-month loan, and most of the loan term on 72- or 84-month terms.

Real-world use cases

1. Choosing a term length

The classic tradeoff. On a $30,000 loan at 7.5%:

48 months: $725/month, $4,810 total interest
60 months: $602/month, $6,107 total interest
72 months: $521/month, $7,512 total interest
84 months: $464/month, $8,990 total interest

The 84-month term cuts the payment by $261/month compared to 48 months — but costs an extra $4,180 in lifetime interest and locks you into a loan longer than most cars stay reliable. Most automotive finance professionals recommend a maximum 60-month term; 72 only if rates are very low.

2. New vs. used pricing

Used cars typically have higher interest rates (often by 1–2 percentage points) but lower depreciation curves. A 2-year-old vehicle has already absorbed the steepest depreciation, so even with a higher rate, total cost of ownership is often lower. Run the calculator on both: a new car at 5.9% APR for 60 months may cost more than a similar 2-year-old version at 7.9% APR over the same term, because the used car price is so much lower.

3. Refinancing your auto loan

If your credit improved after buying — or if market rates fell — you can refinance the auto loan with another lender. Run the math the same way you'd run any refinance: divide refinancing costs (usually minimal for auto loans) by monthly savings to find break-even. Auto loan refinancing typically pays for itself within 6 months if the rate drops by 1.5% or more.

4. Cash vs. finance with a manufacturer 0% offer

Manufacturer 0% APR offers usually require taking the lower rate instead of a cash rebate. Calculate the value of the rebate (say $2,000) against the value of the 0% financing on the cash you'd otherwise owe. If you can earn more than the lost rebate value by keeping cash invested at a comparable rate, the 0% offer wins. If not, take the rebate and finance elsewhere.

Common mistakes

Focusing on monthly payment instead of total cost. A $400/month payment looks cheaper than a $500/month payment until you realize the $400 payment is for 84 months and the $500 payment is for 48 — and costs $4,000 less in total.
Rolling negative equity into the new loan. If you're $5,000 underwater on your current car, rolling that into a new loan means you start the new loan $5,000 upside-down. Better to pay it off separately or wait until you have equity.
Skipping the down payment. A $0 down loan combined with rapid depreciation means owing more than the car is worth on day one. A 10–20% down payment significantly reduces upside-down risk.
Buying gap insurance from the dealer. Gap insurance pays the difference between car value and loan balance if the car is totaled. The dealer's gap insurance markup is significant; most auto insurers offer the same coverage for a fraction of the cost.
Not getting pre-approved. A pre-approval from your bank or credit union gives you negotiating leverage and reveals the true competitive rate before the dealer's financing department gets involved.
Ignoring the total of payments box. Federal law requires the loan disclosure to show "Total of Payments" — the actual amount you'll pay over the life of the loan. Read it before signing.
Forgetting non-financed costs. Insurance, fuel, maintenance, and registration aren't in the loan but hit your monthly budget. Factor them in before deciding what payment you can sustain.

Frequently asked questions

What is a good interest rate on an auto loan?

It depends on credit profile, vehicle age, and loan term. Borrowers with excellent credit (760+) typically see rates from 5–7% on new vehicles, 6–8% on used. Average credit (660–720) ranges from 8–12%. Subprime credit can see 14–24% or higher. Track the average new and used auto loan rates from sources like Edmunds or Cox Automotive to benchmark.

How much car can I really afford?

Conservative guidance: total transportation costs (loan + insurance + fuel + maintenance) under 15–20% of take-home pay. The auto loan portion alone shouldn't exceed 10% of take-home pay. If you make $5,000/month after taxes, that's a $500/month maximum loan payment.

Should I put more money down?

A larger down payment reduces total interest, the size of the loan, and your upside-down exposure during depreciation. Most personal finance experts recommend at least 20% down on a new car and 10% on a used car. That said, depleting savings to put more down isn't worth it — keep an emergency fund intact first.

What is "upside-down" or "underwater" on a car loan?

You're upside-down when the loan balance exceeds the vehicle's market value. It's most common in the first 2–3 years of a 60+ month loan because cars depreciate faster than loans pay down. Being upside-down isn't a problem unless you need to sell or trade in the vehicle, in which case you'd owe the lender the difference.

Is leasing cheaper than buying?

Monthly lease payments are typically lower than monthly loan payments on the same car, but you have nothing to show for the payments at the end of the lease. Buying makes more sense if you drive a lot of miles, plan to keep the car beyond the loan term, or want flexibility to modify the vehicle. Leasing makes more sense if you always want a new car and drive predictable, lower mileage.

Does the calculator account for sales tax in my state?

Sales tax rules vary widely by state. Most states tax the post-trade-in price (which lowers tax), but some tax the full sticker price. The calculator uses a generic input that you can adjust to your state's rules. Always verify with your state's DMV or revenue department before signing.

Can I pay off an auto loan early?

Almost always yes, with no prepayment penalty on loans from major banks, credit unions, and most captive auto lenders. Always confirm the loan agreement before assuming. Paying off early saves all remaining interest from that point forward.

How does APR differ from "money factor" on a lease?

Auto loans use APR. Auto leases use "money factor" — a small decimal number. Multiply the money factor by 2,400 to get the equivalent APR. A money factor of 0.0025 equals 6% APR. The same conversion lets you compare lease cost against loan cost on the same vehicle.

Related Calculixy calculators

From the editorial desk: A car loan is one of the easiest places to lose money quietly. The numbers are simple but the contracts are designed to obscure them. Running your own math before walking into a dealership — checking the financed amount, verifying the APR, calculating total interest — converts the negotiation from a feeling-based exchange ("can I afford this?") to a numbers-based one ("does this deal beat my pre-approval?"). The calculator is the cheapest leverage you'll ever bring to a showroom.

Calculixy's Auto Loan Calculator provides estimates for educational use only and does not constitute a loan offer, financial advice, or a guarantee of approval. Actual rates, payments, and approval depend on your credit profile, the lender's underwriting, vehicle details, and current market conditions. Consult a qualified financial professional before signing any auto loan. All calculations run locally in your browser; Calculixy does not collect or transmit the values you enter.