Car Loan Calculator

What this Car Loan Calculator does

This English-language car loan calculator shows you the real cost of an automobile loan before you sit down with a dealer. Enter the vehicle price, down payment, trade-in value, sales tax rate, doc fees, loan term, and APR — and the tool instantly returns your estimated monthly car payment, the total interest you'll pay, and the exact financed amount your lender will use to structure the deal. 100% client-side — your data never leaves your browser. No uploads, no tracking, no server logs. Most online auto loan calculators get the sales tax math wrong. In most U.S. states the taxable base is (vehicle price − trade-in value), so trading in a $10,000 car on a $35,000 purchase means you only pay tax on $25,000. But California, Virginia, Hawaii, Michigan, Maryland, and a handful of others tax the full vehicle price regardless of trade-in. A few hundred dollars of tax error propagates into every payment estimate downstream. This tool includes a toggle so you match your actual state rule. For a broader look at how compounding affects your total outlay over time, the [compound interest calculator](/en/compound-interest-calculator/) pairs well with this one.

Features

• State-specific trade-in tax credit. A configurable toggle controls whether your state credits the trade-in value against the sales tax base. Most states do; California, Virginia, Hawaii, Michigan, and Maryland don't. Flip the toggle and the financed amount recalculates instantly.
• Full financed-amount breakdown. The results panel shows how the financed amount is assembled: vehicle price − down payment − trade-in + sales tax + fees. You can see exactly which line items are driving your loan total, not just the bottom-line figure.
• Monthly payment and total interest. Uses the standard fixed-rate amortization formula — the same calculation your lender runs — to produce your exact estimated monthly auto payment and the total interest paid over the full term.
• Loan term and APR sensitivity. Adjust the term from 36 to 84 months or change the APR and watch the total interest and monthly payment shift in real time. A 72-month loan at 7% APR can carry nearly double the interest cost of a 48-month loan on the same principal.
• Fees baked in. Doc fees, title, and registration are added to the financed amount before interest is applied, matching how dealers structure the deal — so the payment estimate reflects what you'll actually owe, not a simplified approximation.
• Runs entirely in your browser. All math runs locally using standard browser JavaScript. Period sequencing uses the MDN — Date object; the same browser environment that exposes the Web Crypto API handles everything on your device. Nothing is sent to a server.

How to use the Car Loan Calculator

Fill in each field from top to bottom. Results update instantly — there is no submit button.

1. Enter the vehicle price and down payment. Use the negotiated purchase price. The down payment reduces the principal before any other calculation runs.
2. Add your trade-in and set the tax toggle. Enter your trade-in's estimated value. Then check or uncheck 'My state credits trade-in against the sales tax base' to match your state's rule. When in doubt, leave it checked — it's correct for most states.
3. Enter sales tax, fees, term, and APR. Use your county or state sales tax rate. Add doc fees, title, and registration in the fees field. Set the loan term in months — for example, 60 for a five-year loan — and enter your quoted APR.
4. Read the results panel. Review the financed amount, estimated monthly car payment, total interest, and total loan cost. If the monthly figure is over budget, try a larger down payment or longer term and watch the numbers adjust.
5. Compare scenarios. Run the calculator a second time with a different APR or term. For example, plug in your bank's pre-approval rate, note the total interest, then enter the dealer's quoted rate to see exactly how much more the dealer financing costs over the life of the loan.

Common use cases

• Sanity-checking a dealer's monthly payment quote. Dealers sometimes lead with a monthly payment without disclosing the financed amount. Run your own numbers first: if the dealer's figure is higher than your estimate at the same APR and term, something — an add-on, a bundled product, a higher doc fee — has been folded into the financed amount without your explicit agreement.
• Comparing two auto loan offers. Your credit union offers 5.9% APR for 60 months; the manufacturer's financing arm offers 6.9% for 72 months at a lower monthly payment. This calculator shows which offer costs more in total interest — it's almost always the longer term, even when the monthly payment looks friendlier.
• Modeling down payment trade-offs. A larger down payment lowers the financed amount, cuts total interest, and reduces the risk of going underwater on depreciation. Use this tool to find the minimum down payment that keeps your monthly payment in range while maintaining positive equity from day one.
• Deciding between a cash rebate and 0% APR. Manufacturer promotions often force a choice: take a $2,000 cash rebate and finance through your own bank, or forgo the rebate and accept 0% APR dealer financing. Plug in both scenarios — the better deal depends on your loan size and term. For a complementary view of how opportunity cost accumulates, the [loan calculator](/en/loan-calculator/) handles the general case.
• Setting a purchase price ceiling before you shop. Start with a target monthly payment and adjust the vehicle price until the calculator hits that number at a realistic APR. This gives you a firm ceiling before negotiations begin — in Seattle, Chicago, or anywhere with high local taxes, the fees field alone can shift your ceiling by $1,000 or more.

Frequently asked questions