Auto Loan Calculator: Estimate Your Car Payment

Plan your monthly car payment and amount financed, including the impact of APR, loan term, state sales tax, title/registration and doc fees, cash down, rebates, and trade-in equity or negative equity. The math follows the standard fixed-rate payment formula (same as Excel’s PMT) and the definitions lenders disclose on your Truth-in-Lending form.

Auto Loan Calculator

Vehicle price ($)

APR (%)

APR = rate + certain fees (annualized).

Term (months)

Cash down ($)

Rebate ($)

Reduces taxable/negotiated price in many cases. Confirm with dealer.

Trade-in value ($)

Amount owed on trade-in ($)

If this exceeds trade-in value, the difference is negative equity rolled into the new loan.

Sales tax rate (% of taxable price)

Rules vary by state; see your DMV.

Title/registration & doc fees ($)

Apply trade-in as tax credit (many states)

Some states reduce the taxable base by the trade-in value; others don’t. Verify locally.

Pay fees upfront (don’t finance)

Monthly payment computed via fixed-rate formula (Excel PMT).

Estimated monthly payment$0

Amount financed$0

Total interest (life of loan)$0

Upfront & price components$0

See amortization schedule

Month	Payment	Principal	Interest	Ending balance

What Your Car Payment Includes (and What It Doesn’t)

Principal & Interest (P&I): The loan payment itself (fixed for a fixed-rate auto loan). Computed from the loan amount, APR, and term using the standard annuity formula.
Sales tax: Depends on your state and often applies to the vehicle’s taxable price. Some states give a trade-in sales-tax credit that reduces the taxable base; others don’t. Always confirm with your DMV/state rules.
Title/registration & doc fees: Government and dealer fees required to title and register the car (plus the dealer’s documentation fee). These can be paid up front or rolled into the loan. Amounts and rules vary by state.
Insurance, gas, and maintenance: Not included in the loan payment. Build a separate budget line for ownership costs (insurance is required by law if you finance or lease).

APR vs. Interest Rate — Why APR Drives Comparisons

APR is a standardized measure of the cost of credit that includes the interest rate plus certain fees, expressed as a yearly rate. That’s why regulators require APR disclosures — so you can compare offers “apples-to-apples.” Your Truth-in-Lending disclosure lists APR, finance charge, amount financed, and total of payments.

How the Calculator Works

1) We build the amount financed

Negotiated price minus rebates gives a net price. If your state credits a trade-in for sales tax, the taxable base is reduced by the trade-in value (bounded at the net price). We then add estimated sales tax and fees. Finally we subtract your cash down and trade-in equity (trade-in value minus amount you still owe). If you owe more than the trade-in is worth, the difference is negative equity and increases the loan amount.

2) We compute the monthly payment

Payment for a fixed-rate loan is calculated via the standard formula:

P&I = P × r × (1 + r)ⁿ ÷ [(1 + r)ⁿ − 1]

Where P = amount financed, r = monthly rate (APR ÷ 12), and n = number of payments (term in months). This is the same math used by Excel’s PMT.

3) We display total interest and an amortization snapshot

Over the life of the loan, total interest = (monthly payment × term) − amount financed. The amortization table shows how each payment splits between interest and principal and how the balance falls over time.

Step-by-Step: Estimating Your Payment

Enter the vehicle price and any manufacturer rebate.
Add trade-in details: the value and what you still owe. The calculator handles positive equity (reduces the loan) and negative equity (adds to the loan).
Set sales tax and fees: Use your state’s tax rate and a realistic estimate for title/registration/doc. If your state credits trade-ins against tax, keep the toggle on; if not, turn it off. Use your DMV’s guidance for accuracy.
Choose APR and term: Compare offers from banks, credit unions, online lenders, and dealers. Pre-shopping financing improves negotiating power.
Decide whether to roll fees into the loan or pay up front. Rolling fees in raises the monthly payment and total interest; paying them up front increases cash due at signing.

Smart Settings for 2025 Shoppers

Aim for a shorter term you can afford. Extending to 72–84 months lowers the payment but often costs much more interest and can outlast the car’s warranty. Try 48–60 months if your budget allows.
Watch negative equity. If you’re rolling in a prior balance, consider a slightly cheaper car or larger down payment to avoid owing more than the car is worth.
Focus on “out-the-door” cost, not just monthly payment. Regulators warn that focusing solely on the monthly number can mask a higher overall price or unnecessary add-ons.

Example (illustrative): Price $35,000, rebate $1,000, trade-in $8,000 with $6,000 owed (=$2,000 equity), tax 6% with trade-in credit, fees $450 (financed), down $3,000, APR 6.9%, 60 months → the calculator estimates the amount financed, monthly payment, and total interest. Adjust any input to see the effect.

Negotiating the Deal: Evidence-Based Tips

Shop the loan before the car. Bring a credit union/bank pre-approval and invite the dealer to beat it.
Ask for the Truth-in-Lending figures up front. Compare APR, finance charge, amount financed, and total of payments across offers.
Verify taxes and fees with your state DMV. Avoid under- or over-estimating the out-the-door price.
Understand tax treatment of trade-ins in your state. Many states allow a trade-in credit; some do not. Check official guidance.

Key Formulas (Quick Reference)

Metric	Formula	Notes
Monthly P&I	P×r×(1+r)ⁿ ÷ [(1+r)ⁿ−1]	Standard fixed-rate formula (Excel `PMT`).
Amount financed	(Price − rebate) + tax + fees (if financed) − cash down − trade-in equity	Trade-in equity = trade value − amount owed; negative becomes part of the loan.
Sales tax	Tax rate × taxable base	Taxable base may be reduced by trade-in in many states; verify with DMV.
Total interest	(Monthly payment × term) − amount financed	Shows lifetime cost of borrowing.

Methodology & Disclosures

Calculator math: Fixed-rate payment via the standard formula; taxes and fees modeled per user inputs with an option to apply a trade-in tax credit. Because tax/fee rules vary by state and transaction, confirm figures with your DMV and dealer before signing.
Data sources: Definitions and disclosures from the CFPB (APR, Truth-in-Lending); best-practice buying advice from the FTC; state examples from DMV/DoR pages.
Education only: This article is not financial or legal advice. Verify all numbers on your retail installment sales contract/loan agreement.

Frequently Asked Questions (FAQs)

What’s the difference between APR and the interest rate?

The interest rate is just the cost of borrowing; APR includes the rate plus certain fees, expressed annually, so it’s better for comparing loan offers.

Does trading in a car reduce sales tax?

In many states, yes — your trade-in reduces the taxable price; other states don’t allow the credit. Check your state’s official guidance.

Should I roll fees into the loan?

Rolling fees in raises both the monthly payment and total interest. If you can comfortably pay fees up front, that lowers borrowing costs.

Where should I get financing?

Compare offers. The CFPB and FTC both suggest shopping with banks/credit unions and then letting the dealer try to beat your pre-approval.

Sources