How to use this calculator
- Enter the price you agreed with the dealer, before tax, fees and any rebate, your down payment, a manufacturer’s rebate if you’re taking one, your state and local sales tax rate, and the fees.
- If you’re trading in a car, tick it and enter what the dealer allows for it and what you still owe. Anything you owe above its value is negative equity, and it’s added to the new loan.
- Enter the APR and the term you’re quoted.
- To compare an offer, tick it. For a dealer’s low rate that replaces the rebate, enter its rate and term. For a lease, enter the monthly payment, the months, the cash due at signing (not the part your trade-in or a rebate pays) and the residual value from the lease’s payment calculation.
- Under More options, set whether tax and fees go on the loan, how your state taxes a trade-in or a rebate, the month of your first payment, and a payment you’d like to stay under.
The numbers already filled in are an example. Replace them with your own.
How it's calculated
The amount you borrow follows Regulation Z’s amount financed: the price, minus any rebate, plus sales tax and fees when they go on the loan, minus your down payment and your trade-in’s value, plus what you still owe on the trade-in. Sales tax is your rate on the price after the trade-in and rebate as you set them.
The payment is the level monthly amount that repays that with interest over the term, rounded to the cent. Each payment pays that month’s interest first, a twelfth of the APR on the balance, and the rest pays down the loan; the last payment is whatever is left, so the totals match the schedule to the cent. What you pay in all is your cash at signing plus every payment.
An example
A $42,000 car with $4,000 down, 6% sales tax ($2,520) and $800 of fees added to the loan means borrowing $41,320. At 7.5% for 60 months, the payment is $827.97 a month and the interest comes to $8,358, so you’d pay $53,678 in all. Stretched to 84 months, the payment falls to $633.78 and the interest rises to $11,917.
A dealer’s low rate or the rebate
Manufacturers often offer a low rate or a cash rebate, not both. The calculator prices your loan with the rebate and the dealer’s offer without it, and adds up what each costs in all. In the example, a $2,000 rebate with your own loan costs $51,274; the dealer’s 1.9% costs $47,346. It also values both at your own loan’s rate, which counts when you pay as well as how much, and states the dealer’s offer as a yearly rate counting the rebate: 3.9% here. That rate is not the offer’s APR; it’s what giving up the rebate costs you.
The two measures can disagree when the loans run for different lengths. Your loan with the rebate for 36 months costs $48,031 in all against $51,775 for a 4.9% offer over 72 months, so yours is cheaper in dollars; but the offer amounts to 6.64% a year counting the rebate, less than your 7.5%, because you pay for it more slowly. When that happens the calculator says so and marks neither as the lowest cost.
A lease
A lease is compared with buying over the lease’s months. Leasing costs the cash due at signing, the remaining payments and any charge at the end, which is Regulation M’s total of payments without any part a trade-in or rebate pays. Buying costs your cash at signing and your payments over the same months, less the car’s value at the end minus what you’d still owe; the value is the lease’s residual value unless you enter your own. With the example’s lease quote, leasing costs $22,715 over 36 months and buying costs $27,006. The calculator also shows the end value at which the two cost the same: $29,491 here.
Interest by year
The schedule is split into calendar years from the first payment month you set, which is what the car loan interest deduction for 2025 through 2028 counts. With the example’s first payment in December 2026, you’d pay $258 of interest in 2026.
Assumptions and limits
- Interest is charged monthly, a twelfth of the APR on the balance, with the first payment a month after you sign. If your loan charges interest by the day, a first payment more than a month away, or a late one, adds a little interest.
- The rate is the APR you’re quoted and stays the same for the whole loan. A variable rate, a deferred first payment and a balloon payment aren’t modeled.
- Sales tax is one rate, on the price after the trade-in, any cap on the trade-in credit and the rebate as you set them; fees aren’t taxed. States differ on all of these, and some cap the trade-in credit: Michigan’s cap is $12,000 in 2026.
- Fees are added to the loan or paid at signing; add-ons such as a service contract or GAP coverage can go in the fees.
- The dealer’s offer is compared only if you qualify for it, could take the rebate with your own financing instead, and it needs the same down payment.
- Totals are added up in dollars, and the dealer’s offer is also valued at your own loan’s rate. What your cash could earn meanwhile isn’t counted.
- A lease is entered as its quote states it; its payment isn’t worked out from a money factor. The comparison leaves out mileage and wear charges, insurance and maintenance, and the car loan interest deduction, and assumes both quotes are for the same car with the same trade-in. The car’s value at the end is the lease’s residual value, the leasing company’s estimate, unless you enter your own; there’s no estimate of how fast a car loses value.
- The deduction is described, and the interest you’d pay each year is shown, but what it saves you in tax isn’t worked out here.
- The term table holds the rate the same for every length.
- The default rate is the Federal Reserve’s average for a 60-month new car loan at commercial banks, 7.54% in August 2026, rounded to 7.5%; the default price and down payment finance about the average amount financed on a new car loan in the same release. The sales tax rate, fees and the offers are examples.
Input field details
What to enter in each box, where to find the number, and how this calculator treats it. When two calculators give different answers from the same numbers, it's usually because they handle one of these differently.
Price of the car
The price you agreed with the dealer, before sales tax, fees and any rebate.
Where to find itThe buyer’s order or purchase agreement. If the dealer quoted a price with a rebate already taken off, enter the price before it and the rebate in its own field, or the rebate counts twice.
How this tool treats itThe amount financed is what you borrow: the price, less any rebate, plus the tax and fees you add to the loan, less your down payment and your trade-in’s value, plus anything you still owe on the trade-in. With no finance charge paid up front, it is the "Amount Financed" on a car loan’s federal disclosure.
Allowed range$1,000 to $1,000,000
Down payment
The cash you put down toward the car.
Where to find itThe buyer’s order, "cash down" or "down payment".
How this tool treats itEnter the cash only. A trade-in goes in its own fields, though federal lending rules count a trade-in’s value as part of the down payment.
Allowed range$0 to $1,000,000
Rebate
A manufacturer’s cash rebate you would take on this car.
Where to find itThe dealer’s offer sheet or the manufacturer’s current incentives.
How this tool treats itA rebate is cash back from the maker that comes off the price you pay. It lowers your loan, not the price the tax is worked out on, unless you turn on taxing the price after the rebate. A rebate larger than the price is read as the price. If the dealer offers a lower rate instead of the rebate, tick that offer to compare the two.
Allowed range$0 to $50,000
Sales tax rate
The combined state and local sales tax rate where you register the car, to two decimals.
Where to find itYour state’s revenue department, or the tax line of the dealer’s buyer’s order divided by the taxed price.
How this tool treats itThe tax is the rate times the taxed price, rounded to the cent. Fees are not taxed. How a trade-in and a rebate change the taxed price is set under More options, because states differ.
Allowed range0% to 15%
Not includedState rules beyond the rate and the switches, such as a tax on fees or a different rate for vehicles.
Fees
Title, registration and dealer fees, plus any add-ons you are buying, such as a service contract or GAP coverage.
Where to find itThe buyer’s order, the lines below the vehicle price.
How this tool treats itFees are added to the loan or paid at signing, as you choose under More options. They are not taxed.
Allowed range$0 to $50,000
I’m trading in a car
Tick it if the dealer is taking your current car as part of the deal.
Trade-in value
What the dealer allows you for your current car.
Where to find itThe buyer’s order, "trade-in allowance".
How this tool treats itThe trade-in value is the amount the dealer credits for your old car. It comes off what you borrow, and by default off the price the tax is worked out on.
Allowed range$0 to $500,000
Still owed on it
The payoff amount on your current car’s loan, or 0 if it is paid off.
Where to find itYour current lender’s payoff quote.
How this tool treats itIf you owe more than the car is worth, the difference is negative equity. It is added to the new loan, so you borrow it again and pay interest on it. The trade-in value and what you owe are entered separately so that amount shows on its own line.
Allowed range$0 to $500,000
Rate (APR)
The annual percentage rate the lender quotes you, to two decimals.
Where to find itThe "Annual Percentage Rate" box on the loan’s federal disclosure, or your preapproval letter.
How this tool treats itThe APR is the yearly cost of the credit as a rate. Each month’s interest is a twelfth of it on the balance, rounded to the cent and paid before principal. With no other finance charge, the interest over the loan is its finance charge: the "Finance Charge" box on the disclosure.
Allowed range0% to 30%
Not includedA rate that changes, interest charged by the day, and a first payment more or less than a month after you sign.
Loan term
The number of monthly payments on the loan.
Where to find itThe loan’s disclosure, "Number of Payments", or the lender’s quote.
How this tool treats itThe payment is the level amount that repays the loan over the term, rounded to the cent; the last payment is whatever is left, so the balance ends at $0. The total of payments is every payment added up: what you will have paid when you have made them all. A longer term lowers the payment and raises the interest.
Allowed range12 to 96 months
The dealer’s lower rate instead of the rebate
Tick it if the dealer offers a low rate in place of the rebate, to see which costs you less.
How this tool treats itThe comparison assumes you qualify for the low rate, can take the rebate with your own financing instead, and need the same down payment for both.
Dealer’s rate
The APR of the dealer’s low-rate offer, to two decimals.
Where to find itThe dealer’s or manufacturer’s offer.
How this tool treats itThe two choices are added up in dollars. The dealer’s offer is also shown as a yearly rate counting the rebate: the rate at which its payments repay what you would borrow with the rebate. Below your own loan’s rate, the dealer’s offer is the cheaper money, which counts when you pay as well as how much. This yearly rate is not the offer’s APR.
Allowed range0% to 30%
Dealer’s term
The number of monthly payments on the dealer’s offer.
Where to find itThe dealer’s or manufacturer’s offer. Low rates are often limited to shorter terms.
Allowed range12 to 96 months
A lease quote
Tick it if you have a lease quote on the same car, to compare leasing with buying.
How this tool treats itThe comparison assumes both quotes are for the same car with the same trade-in.
Lease payment
The monthly payment, with tax, as the quote prints it.
Where to find itThe lease quote or the lease’s federal disclosure, "Monthly Payments".
Allowed range$0 to $20,000
Lease months
The length of the lease in months.
Where to find itThe lease quote or disclosure.
How this tool treats itEverything is compared over these months. Leasing costs the cash due at signing, the monthly payments not already in it, and any charges at lease end. Buying costs the cash you pay at signing and the loan payments made in these months, plus what you would still owe at the end, less the car’s value then. The lower cost over the lease’s months ranks first.
Allowed range12 to 60 months
Cash due at signing
The cash part of the amount due when you sign the lease.
Where to find itThe lease’s "Amount due at lease signing". Leave out any part your trade-in or a rebate pays, and any refundable security deposit.
How this tool treats itThe cash due at signing is what you hand over when the lease starts. The trade-in and any rebate are counted for neither the lease nor the loan, so only the cash goes here.
Allowed range$0 to $100,000
Residual value
The car’s value at the end of the lease that the payment was worked out from.
Where to find itThe lease’s payment calculation, "Residual value".
How this tool treats itThe residual value is the leasing company’s estimate of what the car will be worth when the lease ends. It is used as the car’s value if you buy instead, unless you enter your own under More options.
Allowed range$0 to $1,000,000
Tax and fees
Whether you add the sales tax and fees to the loan or pay them at signing.
How this tool treats itAdded to the loan, you pay interest on them. Paid at signing, they are part of the cash you pay that day.
Tax the price after the trade-in
Leave it on if your state taxes only the price minus your trade-in’s value; turn it off if it taxes the full price.
Where to find itYour state’s revenue department.
Cap on the trade-in credit
The most of a trade-in’s value your state lets come off the taxed price, or 0 if there is no limit.
Where to find itYour state’s revenue department. Michigan’s limit is $12,000 in 2026.
Allowed range$0 to $500,000
Tax the price after the rebate
Turn it on if your state taxes the price after a manufacturer’s rebate is taken off.
Where to find itYour state’s revenue department.
First payment month
The month and year of your first payment.
Where to find itThe loan’s disclosure, "When Payments Are Due", or the lender’s welcome letter.
How this tool treats itPayments fall in the months after it, which sets the interest you pay in each calendar year; the payment and totals do not change. You are taken to have signed the month before. Interest on a loan for a qualifying new car taken out after 2024 may be deductible from 2025 through 2028, up to $10,000 a year, so the interest you’d pay in those years is listed.
Payment you’d like to stay under
The most you want to pay a month, or 0 to leave it out.
How this tool treats itShows the highest whole-dollar price whose payment stays at or under it, with everything else as you entered it.
Allowed range$0 to $20,000
First payment is in the cash due
Leave it on if the cash due at signing includes the first monthly payment; the quote’s itemization of the amount due at signing shows whether it does.
Where to find itThe lease’s itemization of the amount due at signing.
Charges at lease end
A disposition fee or other charge you would pay when you return the car.
Where to find itThe lease’s disclosure of fees at the end of the term.
Allowed range$0 to $20,000
Not includedCharges for extra miles or wear, which depend on how you drive.
Car’s value when the lease ends
What you think the car will be worth when the lease ends, or 0 to use the residual value.
How this tool treats itThe buy-or-lease result also shows the end value at which the two cost the same.
Allowed range$0 to $1,000,000
Questions
How is a car payment calculated?
Is 0% or low-rate financing better than a rebate?
Should I lease or buy?
How much car can I afford?
What happens to negative equity when I trade in a car?
Should I take a 72- or 84-month car loan?
Is car loan interest tax-deductible?
Should I put the sales tax and fees on the loan?
Version history
- October 24, 2026 (version 1.0.0): First version. A car loan’s payment, interest and total with tax, fees, a rebate and a trade-in, a dealer’s low rate weighed against its rebate, a lease quote against buying, and the interest by calendar year.