Auto loan calculator
A car payment calculator that handles what the big ones skip: your trade-in, the loan you still owe on it, and your state's sales tax rules — computed instantly as you type.
Monthly payment
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- Amount financed
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- Sales tax
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- Total interest
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- Total cost of loan
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- Paid off
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Amortization schedule
How the payment formula works
Every fixed-rate auto loan uses the same amortization formula, the one this calculator and every lender's system runs:
M = P × r(1+r)n / ((1+r)n − 1)
P is the amount financed, r is your APR divided by 12, and n is the term in months. At 0% APR the payment is simply P ÷ n. The amount financed is where car loans get interesting — it's the vehicle price plus sales tax and fees, minus your down payment and trade-in value, plus anything you still owe on the trade-in.
Worked example
A $32,000 car in Texas with a $4,000 trade-in and $2,000 down, financed for 60 months at 6.9% APR. Texas taxes the price minus the trade-in, so tax is 6.25% of $28,000 = $1,750. Amount financed: $32,000 + $1,750 − $2,000 − $4,000 = $27,750. The formula gives a monthly payment of $548.17, and over five years you pay $5,140.53 in interest.
Auto loan calculator with trade in and tax
Most states charge sales tax on the vehicle price minus your trade-in allowance, which makes a trade-in worth more than its sticker value. But the rule isn't universal: California, Hawaii, Kentucky, Maryland, Michigan, Virginia and DC tax the full price with no trade-in credit, and Illinois caps the credit at $10,000. Pick your state above and the calculator applies the right treatment automatically — and tells you which rule it used. Rates shown are 2026 state-level rates; local county and city taxes can add more, so edit the rate field if you know your combined rate.
Auto loan calculator with negative equity
If you owe more on your current car than it's worth, the difference doesn't disappear — the dealer rolls it into the new loan. Enter your trade-in's value and the loan balance still on it: the calculator adds the shortfall to the amount financed and flags it clearly. Rolling $3,000 of negative equity into a 60-month loan at 7% costs about $560 in added interest on top of the $3,000 itself.
Car payment calculator with extra payments
The monthly payment is the number dealers negotiate with, but total interest is the number you actually pay. A longer term shrinks the payment while quietly growing the cost. Extra principal payments attack that directly: in the example above, an extra $100 a month pays the loan off ten months early. Use the extra-payment field and watch the payoff date and interest-saved figures update live.
72 month car loan calculator
Six- and seven-year loans (72 and 84 months) now make up a large share of new-car financing because they minimize the monthly payment. Select the 72 or 84 preset and compare total interest against 48 or 60 months: on a $30,000 loan at 7%, stretching from 60 to 72 months cuts the payment by about $83 but adds roughly $1,100 of interest — and keeps you underwater on the car longer.
How much car can I afford
A common rule of thumb is to keep all car costs — payment, insurance, fuel — under 15–20% of take-home pay. Work backwards: pick a payment you're comfortable with, then adjust the price field until the result matches. The CFPB's auto loan guide is a good deeper read before you shop.
Frequently asked questions
How does an auto loan calculator with trade in and tax work?
Enter the vehicle price, your trade-in value and your state. The calculator subtracts the trade-in where your state allows it, applies the state sales tax rate, adds fees, and finances the rest. The monthly payment uses the standard amortization formula lenders use.
Can a car payment calculator with extra payments show my payoff date?
Yes. Add an amount in the extra monthly payment field and the calculator recomputes the payoff date, shows how many months you cut from the loan, and how much interest you save. Extra payments go straight to principal.
How does an auto loan calculator with negative equity work?
If you owe more on your trade-in than it is worth, the shortfall is added to the new loan. Enter the trade-in value and the amount still owed; the calculator rolls the difference into the amount financed and warns you it is happening.
What does a 72 month car loan calculator show?
Pick the 72-month preset to see the lower monthly payment and the higher total interest a six-year term produces. Compare it against 48 or 60 months — the payment falls, but the total cost of the car rises.
Is it better to put money down or trade in?
A dollar of down payment and a dollar of trade-in equity reduce the loan equally, but in most states the trade-in also cuts your sales tax, because tax applies to the price minus the trade-in. In those states trading in saves slightly more; in states with no trade-in credit they are equivalent.