Auto Loan Calculator
Estimate your monthly car payment the way a dealership actually structures the deal: vehicle price, minus trade-in and down payment, plus sales tax and fees financed into the loan — with total interest and the true all-in cost of the vehicle.
Car payment
Example: $35,000 car, $5,000 trade-in, $3,000 down at 7% for 5 years ≈ $580.18/mo.
Companion guide: Fee-adjusted APR explained works through the other way this site's engine handles fees — subtracted from the amount received and restated as an annual rate — on a fictional loan. This calculator adds fees to the amount financed instead and charges interest on them. Every explainer on the site is listed under Guides.
How the amount financed is built
The calculator starts from the vehicle price, subtracts the trade-in and the down payment, and adds sales tax and fees — so whenever tax or fees are above zero, the amount financed is larger than the price minus what you put down. In the worked example — call it Example A — a fictional $35,000 car with a $5,000 trade-in and $3,000 down, an illustrative 6% sales-tax rate, and $500 of fees — tax applies to the $30,000 left after the trade-in, making $1,800 of tax, and the amount financed is $29,300. At 7% over 60 months the payment is $580.18 a month; the schedule charges $5,511 of interest, and the total cost of the vehicle — down payment, trade-in, and every loan payment — is $42,811. Every figure on this page is computed when the page is built by the same tested engine that powers the calculator above; the prices, rates, and fees are illustrative inputs chosen for the arithmetic, not quotes.
What the engine computes, step by step
The form hands your inputs to one engine function, which validates them, runs the steps below in order, and returns a typed result — or an explicit, human-readable error. The interface only formats what comes back; it never does arithmetic of its own.
- Validation. The price must be greater than zero; the down payment, trade-in, and fees cannot be negative; the tax rate must fall inside the engine's range. A value that fails is refused before any arithmetic runs, with the engine's own message.
- Taxable base and sales tax. The base is the price minus the trade-in, never below zero — $35,000 − $5,000 = $30,000 here — and the tax is that base times the rate you enter: $30,000 × 6% = $1,800. The engine's note on this field calls it the common US convention and adds that some states tax the full price.
- Amount financed = price − trade-in − down payment + sales tax + fees: $29,300. At zero or less the engine stops with its own message rather than a number: "The down payment and trade-in cover the whole purchase — no loan is needed."
- The payment applies the standard amortized-loan (PMT) formula with monthly compounding — the convention behind US mortgages and most consumer loans — to the amount financed. The annual rate ÷ 12 is the monthly rate, 0.5833% at 7%, and years × 12 is the number of payments, 60 here. The result, $580.18, is the one fixed amount that retires the balance exactly at the last payment; the How the monthly payment formula works guide derives it.
- The schedule is then computed one month at a time: each month the engine charges interest on the balance still outstanding, and the remainder of the fixed payment reduces the principal. Total interest is the sum of every month's charge, $5,511; the total of payments is the amount financed plus that interest, $34,811.
- Total cost of the vehicle = down payment + trade-in + total of payments: $42,811. The engine's definition is everything paid over the deal, trade-in included.
Month one, and the year-by-year schedule
In month one of Example A the balance is the whole $29,300, so interest is $29,300 × (7% ÷ 12) = $170.92, and the remaining $409.26 of the $580.18 payment reduces the principal: 29.5% of the first payment is interest. In Example A — at this rate and term — the principal share exceeds the interest share from the first month, and it grows as the balance falls. Year 1 records $1,890 of interest against $5,072 of principal; year 5 records $257 against $6,705. Nothing is front-loaded by anyone; the interest charge follows the balance.
| Year | Interest paid | Principal paid | Balance at year end |
|---|---|---|---|
| 1 | $1,890.33 | $5,071.77 | $24,228.23 |
| 2 | $1,523.69 | $5,438.41 | $18,789.82 |
| 3 | $1,130.55 | $5,831.55 | $12,958.27 |
| 4 | $708.99 | $6,253.12 | $6,705.15 |
| 5 | $256.95 | $6,705.15 | $0.00 |
| Whole term | $5,510.51 | $29,300.00 | — |
The principal column sums to the amount financed and the interest column to the total-interest line, because the schedule is the source of both. The Reading an amortization schedule guide walks through rows like these, and the Amortization Calculator shows them for any inputs.
The five terms the menu offers
The table runs Example A through each of the five terms the menu offers, 36 to 84 months — one engine call per row — with a final column for the balance still owed after 36 payments.
| Term | Monthly payment | Total interest | Total cost of the vehicle | Owed after 36 payments |
|---|---|---|---|---|
| 36 months | $904.70 | $3,269 | $40,569 | $0 |
| 48 months | $701.62 | $4,378 | $41,678 | $8,109 |
| 60 months | $580.18 | $5,511 | $42,811 | $12,958 |
| 72 months | $499.54 | $6,667 | $43,967 | $16,178 |
| 84 months | $442.22 | $7,846 | $45,146 | $18,467 |
Each step to a longer term lowers the payment and raises the total interest, because the balance is outstanding — and charged interest at the monthly rate — for more months. Moving from 60 to 84 months lowers the payment by $137.96 and raises total interest by $2,336, the charge for carrying a balance for 24 additional months. After 36 payments the 36-month schedule is paid off, the 60-month schedule still owes $12,958, and the 84-month schedule $18,467. The engine compares; whether a lower payment over more months or a higher payment over fewer fits a budget is not a question the arithmetic answers.
What the down payment, trade-in, and fees each change
Down payment. Each dollar of down payment lowers the amount financed by one dollar and nothing else — not the taxable base, not the tax. Raising Example A's down payment by $1,000 lowers the amount financed to $28,300, the payment by $19.80 a month, and total interest by $188.
Trade-in. A trade-in lowers the amount financed dollar for dollar and also lowers the taxable base. Enter Example A's $5,000 trade-in as down payment instead — $8,000 down, trade-in blank — and the engine taxes the full $35,000: the tax rises from $1,800 to $2,100 and the amount financed from $29,300 to $29,600, exactly $300 more.
Fees. The fees field is one number the engine adds to the loan; it does not decide which charges belong in it. With Example A's fees at $0 the amount financed is $28,800, the payment $570.27 — $9.90 a month less — and total interest $94 lower: the interest the schedule charges on $500 over 60 months. The APR Calculator treats fees differently — as upfront charges restated as an annual rate, without changing the payment — and the Fee-adjusted APR explained guide works through that arithmetic. The rate field on this page is the note rate the payment is computed from.
The reference figure, recomputed
The methodology page names the figure the payment engine is validated against: a $200,000 loan at 6% over 30 years. Recomputed when this page is built, the function this calculator hands the amount financed to returns a payment of $1,199.10 and total interest of $231,676, as the methodology page and the automated tests expect. If the copy and the code ever disagreed, the site would fail to build rather than publish inconsistent numbers.
How to read the result
- The large "/ month" figure is the fixed payment on the amount financed, to the cent — $580.18 in Example A.
- Amount financed is price − trade-in − down payment + tax + fees, in whole dollars — $29,300 here.
- Sales tax (financed) appears only when the tax is greater than zero — $1,800 here — and is already inside the amount financed.
- Total interest is the sum of the schedule's monthly charges, in whole dollars — $5,511 here. The total of payments is the amount financed plus the schedule's total interest — $34,811 here — not the displayed payment times the term, which would differ by a few cents because the schedule multiplies the unrounded figure.
- Total cost of the vehicle is down payment + trade-in + every loan payment — $42,811 here — including the financed tax and fees.
Money is shown to the cent, or to whole dollars for large totals like lifetime interest; internally every calculation keeps the full precision of IEEE-754 double-precision arithmetic, and nothing is rounded between steps. Your lender's figure may differ by a few cents depending on their rounding and day-count conventions — the difference is presentational, not an error.
Where the calculator stops
The limits are the engine's, and the methodology page states them. The calculators model fixed-rate, fully amortizing loans. They do not model adjustable-rate mortgages, interest-only periods, balloon payments, or negative amortization: whatever rate you enter is held fixed for every month of the term. The vehicle's value over time is not modelled, so the engine reports what is owed, never what the car is worth. The fees field is a single total; the engine does not decide which charges belong in it, and it does not know your lender's day-count or rounding conventions. There is no extra-payment input — the Mortgage Payoff Calculator runs that comparison. Inputs are validated before any arithmetic runs and refused with the engine's own messages: a price of zero, "The vehicle price must be greater than 0." A negative trade-in, "The trade-in value cannot be negative." A tax rate beyond the engine's range, "Enter a sales-tax rate between 0 and 30 percent." And a correct calculation can still be the wrong calculation for your situation — choosing the right loan for a real-world decision is judgment we cannot automate.
Frequently asked questions
Why is the amount financed bigger than the car price minus my down payment?
Because the engine adds sales tax and fees after subtracting the trade-in and the down payment. In Example A, price − trade-in − down payment is $27,000 — what the calculator reports with the tax rate and the fees both at zero — and with 6% tax on the $30,000 base plus $500 of fees it is $29,300. The gap, $2,300, is the tax plus the fees, and interest is charged on it.
How is the sales tax worked out?
As the price minus the trade-in, times the rate you enter — the engine's note calls this the common US convention and adds that some states tax the full price: $30,000 × 6% = $1,800 in Example A. To model a full-price tax, leave the trade-in blank and add its value to the down payment: the tax becomes $2,100 and the amount financed $29,600.
What does "Total cost of the vehicle" include?
The down payment, the trade-in value, and every loan payment — everything paid over the deal, in the engine's definition: $3,000 + $5,000 + $34,811 = $42,811 in Example A. Financed tax and fees sit inside the loan payments; fees entered as zero are left out, because the engine has no field for money paid at signing.
What happens if I enter zero in the fees field?
Only the amount financed changes, by the fees: $28,800 instead of $29,300, a payment of $570.27 instead of $580.18, and $94 less total interest — the interest the schedule charges on $500 when it is financed. The engine reports both cases; it does not weigh one against the other.
What changes when I pick a longer term?
The payment falls and the total interest rises, because the balance is charged interest at the annual rate ÷ 12 for more months: on Example A's $29,300, 84 months instead of 60 lowers the payment from $580.18 to $442.22 and raises total interest from $5,511 to $7,846, and after 36 payments the 84-month schedule still owes $18,467 against $12,958. The engine computes the five terms; it does not pick one.
Does the calculator tell me whether I would be "upside down"?
No. Being upside down means owing more than the car is worth, and the vehicle's value is not an input. The engine does provide the balance owed at each year end — $24,228 after year 1 and $18,790 after year 2 in Example A; comparing those with what the car could be sold for is a judgment outside the arithmetic.
What happens if I enter 0% as the rate?
The payment formula divides by the rate, so the engine treats zero as a separate case and divides the amount financed evenly across the term: $29,300 ÷ 60 = $488.33 a month, with $0 of interest. Tax and fees do not depend on the rate, so the amount financed is unchanged.
Why might my lender's payment differ from the calculator by a few cents?
Internally the engine keeps the full precision of IEEE-754 double-precision arithmetic and rounds only on screen, to the cent (or to whole dollars for large totals like lifetime interest). Your lender's figure may differ by a few cents depending on their rounding and day-count conventions — the difference is presentational, not an error.
Not financial advice: a general educational estimate. Sales-tax rules vary by state (some tax the full price before trade-in), and actual rates depend on your credit. Values are processed locally in your browser and never transmitted. See the methodology page.