Car Loan Interest Rate Calculator

Q: How does the calculator figure out my monthly car payment?

It uses the standard amortized loan formula: M = P × i ÷ (1 − (1 + i) −n ) P = amount you finance i = APR divided by 12 n = number of months This is the same math banks, credit unions, and dealers use, so your quote should be very close.

Updated Aug 7, 2026 By Jehan Wadia

Introduction

This Car Loan Interest Rate Calculator shows what a car loan will really cost you each month and over time. Type in the car price, your down payment, trade-in value, interest rate (APR), and loan term. The calculator does the rest.

You get your monthly car payment, total interest paid, and the full amount financed. It also adds sales tax and dealer fees, so the number you see is close to what you will actually pay.

The tool goes further than a basic auto loan calculator. It shows a step-by-step math breakdown, charts of your loan balance over time, and a full month-by-month car loan amortization schedule. You can compare two loan offers side by side, check typical rates for your credit score, and see how much you save by paying a little extra each month.

Use it before you visit a dealer or sign anything. A small change in rate or term can cost or save you thousands of dollars. If you are still setting a budget, start with the car affordability calculator to see what price range fits your income.

How to use our Car Loan Interest Rate Calculator

Enter the car price, your down payment, trade-in, interest rate, and loan term. The calculator shows your monthly car payment, total interest, total cost, effective APR, and a full month-by-month amortization schedule.

Vehicle Price: Type the price you agreed to pay for the car, before tax and fees. You can also drag the slider. The car price calculator can help you sanity-check a dealer quote.

Down Payment ($ or %): Enter the cash you pay up front. Type a dollar amount or a percent — the other box updates on its own. Not sure how much to put down? Try the down payment calculator.

Trade-In Value: Enter what the dealer gives you for your old car. Use the net value after you pay off any old loan. The trade-in value calculator and used car value calculator give you a realistic starting figure.

Loan Amount: This fills in for you: price plus tax and fees, minus your down payment and trade-in. Tick "Override loan amount manually" if you want to type your own number.

Annual Interest Rate (APR): Enter the yearly rate your lender offers. If you don't have an offer yet, use the credit tier rate below, or work backwards from a payment with the loan interest rate calculator.

Loan Term: Pick how many months you will pay, from 12 to 84. Longer terms lower the monthly payment but raise total interest.

Credit Score Range: Choose your credit tier to see the APR range buyers like you usually get. Click "Use Midpoint Rate" to drop that rate into the box.

First Payment Date: Pick the month and year of your first payment. This sets the dates in the schedule and your payoff date.

Include Sales Tax and Sales Tax Rate: Leave the switch on and enter your local tax rate. Tax is charged on the price minus your trade-in. Use the sales tax calculator if you need to look up a combined state and local rate.

Include Additional Fees and Additional Fees: Leave the switch on and enter dealer fees like doc, title, and registration. These get added to the loan — the DMV fee calculator helps you estimate title and tag costs.

Compare Scenarios: Turn this on to test a second loan. Enter a price, down payment, trade-in, APR, term, tax rate, and fees for Scenario B to see which deal costs less.

Extra Monthly Payment: Enter any extra cash you plan to add each month to see how much interest and time you save. The extra payment calculator runs the same idea on any loan type.

One-Time Lump Sum: Enter a single big payment you plan to make, such as a bonus or tax refund.

Lump Sum Applied At Payment #: Type which payment number the lump sum lands on, from 1 up to your last payment.

Calculate and Reset: Results update as you type, but you can click Calculate any time. Click Reset to return to the starting values.

Car Loan Interest Rates Explained

A car loan lets you borrow money to buy a vehicle and pay it back in monthly payments. The interest rate is the extra amount the lender charges you for that loan. It is shown as an APR, or annual percentage rate. A lower APR means you pay less for the same car.

How Car Loan Interest Works

Most car loans are amortized. That means each monthly payment is split into two parts: some goes to interest, and the rest goes to the loan balance (the principal). Early on, more of your payment goes to interest. As the balance drops, more goes to principal. By the last payment, the loan hits zero. The amortization calculator shows this split for any loan, and the simple interest calculator shows how a non-amortized loan differs.

Lenders find the monthly interest by dividing the APR by 12. So a 7.25% APR is about 0.604% per month. That monthly rate is charged on whatever you still owe. Our car interest calculator and loan payment calculator use the same formula.

What Changes Your Rate

Credit score: Higher scores get lower rates. A buyer with excellent credit may pay 4–6%, while a buyer with poor credit may pay 18% or more. Keeping your credit utilization low helps.
Loan term: Longer loans (72 or 84 months) usually have higher rates and much more total interest, even though the monthly payment looks smaller.
Down payment and trade-in: Putting more money down lowers the amount you borrow, which cuts interest and can help you get a better rate.
New vs. used car: Used cars almost always carry higher rates than new ones — see the used car loan calculator for typical used-vehicle terms.
Lender type: Banks, credit unions, and dealer financing all offer different deals. Credit unions are often the cheapest; compare with the Navy Federal auto loan calculator or the Bank of America auto loan calculator.
Debt load: Lenders check your debt-to-income ratio before approving a rate.

What Gets Added to the Loan

The sticker price is not the whole story. Sales tax, doc fees, title, and registration are often rolled into the loan. That raises the amount you finance, so you pay interest on those costs too. In many states, your trade-in value is subtracted before tax is figured, which saves you money. Don't forget running costs either — check the car insurance calculator and fuel cost calculator before you commit.

Loan-to-Value and Being Upside Down

Loan-to-value (LTV) compares what you borrow to what the car is worth. If your LTV is over 100%, you owe more than the car's value. This is called being upside down or having negative equity. It is risky, because cars lose value fast — the car depreciation calculator shows how quickly — and you could still owe money after a crash or trade-in.

APR vs. Effective APR

The rate a dealer quotes may not include fees. When fees are financed, your real cost is higher. The effective APR spreads those fees into the rate so you can compare offers fairly. Always check the APR, not just the monthly payment. Our APR calculator breaks this down further, and the car lease calculator lets you weigh leasing against buying.

Ways to Pay Less Interest

Pick the shortest term you can afford.
Make a bigger down payment, ideally 20%.
Get pre-approved by a bank or credit union before you shop.
Add extra money to each payment, or make a lump-sum payment. Both cut months off the loan and save interest — see the auto loan payoff calculator.
If rates drop or your credit improves, run the numbers through the auto refinance calculator.
Check that your loan has no prepayment penalty.

Financing something other than a car? Try the motorcycle loan calculator, RV loan calculator, boat loan calculator, or the general-purpose loan calculator.

Formulas used

Sales Tax Amount

\text{Tax} = (\text{Price} - \text{Trade-In}) \times \frac{t}{100}

Amount Financed (Loan Principal)

P = \text{Price} + \text{Tax} + \text{Fees} - \text{Down} - \text{Trade-In}

Monthly Periodic Interest Rate

i = \frac{\text{APR}\%}{12 \times 100}

Monthly Payment (Amortized Loan)

M = \frac{P \cdot i}{1 - (1+i)^{-n}} \quad\text{(and } M = \frac{P}{n} \text{ when } i = 0\text{)}

Total of Payments and Total Interest

\text{Total} = M \times n, \qquad \text{Interest} = M \times n - P

Effective APR (fees as prepaid finance charge)

P - \text{Fees} = M \cdot \frac{1-(1+i_e)^{-n}}{i_e}, \qquad \text{APR}_{e} = 12 \cdot i_e \times 100\%

Amortization Schedule (per payment)

I_k = B_{k-1} \cdot i, \qquad \text{Prin}_k = (M + \text{Extra} + \text{Lump}_k) - I_k, \qquad B_k = B_{k-1} - \text{Prin}_k

Loan Ratios: LTV, Interest Share, Cost per $1,000

\text{LTV} = \frac{P}{\text{Price}} \times 100\%, \quad \frac{\text{Interest}}{\text{Price}} \times 100\%, \quad \text{Per\$1k} = \frac{\text{Interest}}{P} \times 1000

Frequently asked questions

How does the calculator figure out my monthly car payment?

It uses the standard amortized loan formula:

M = P × i ÷ (1 − (1 + i)⁻ⁿ)

P = amount you finance
i = APR divided by 12
n = number of months

This is the same math banks, credit unions, and dealers use, so your quote should be very close.

Why is my effective APR higher than the rate I typed in?

Because fees are rolled into the loan. You borrow the fee money and pay interest on it. The effective APR spreads those fees back into the rate so you see your true cost. If you enter $0 in fees, the effective APR matches the rate you entered.

What is the difference between the interest rate and the APR?

The interest rate is only the cost of borrowing. The APR adds lender fees on top of that rate. APR is the better number for comparing two offers, because a low rate with big fees can cost more than a higher rate with none.

Is sales tax charged before or after my trade-in?

This calculator subtracts the trade-in first, then applies tax. Most states work this way, so a $3,000 trade-in on a $35,000 car means you only pay tax on $32,000. A few states tax the full price. Check your state rules if the number looks off.

Does this calculator work for a 0% APR dealer deal?

Yes. Enter 0 in the APR box. The tool then divides the amount financed by the number of months, and total interest shows as $0.00. You still pay tax and fees, so your monthly payment will be higher than price ÷ months.

What does "Cost Per $1,000 Borrowed" mean?

It shows how much interest you pay for every $1,000 you finance. It is a quick way to compare loans of different sizes. If one loan costs $195 per $1,000 and another costs $140, the second is cheaper, no matter the price of the car.

Why does most of my early payment go to interest?

Interest is charged on what you still owe. At the start you owe the most, so the interest slice is biggest. As the balance drops, the interest shrinks and more of the same payment goes to principal. You can watch this shift month by month in the amortization table.

Can I use this calculator for a used car?

Yes. Enter the used car price and the APR the lender quoted you. Used car rates are usually 1% to 3% higher than new car rates, and terms are often shorter, so pick the term the lender actually offers.

What if I have no down payment or no trade-in?

Just enter 0 in those boxes. The full price, plus tax and fees, gets financed. Your loan-to-value will likely go over 100%, which means you owe more than the car is worth. The calculator flags this for you.

What is the "Override loan amount manually" checkbox for?

Tick it when a lender gives you an exact amount financed that does not match the auto math. Common reasons include negative equity from an old loan, a gap insurance add-on, an extended warranty, or a rebate. Once ticked, you can type any figure you want.

How much should I put down on a car?

Aim for 20% on a new car and 10% on a used one. That keeps your loan-to-value under 100%, so you are not upside down while the car loses value. Use the percent box to test 10%, 15%, and 20% and see how the payment and total interest drop.

Is a 72 or 84 month car loan a bad idea?

The payment looks small, but you pay far more interest and stay upside down for years. Switch the term slider between 60 and 84 months and watch the total interest number. If you can only afford the car at 84 months, the car is likely too expensive.

Where does my extra payment go?

Straight to the principal, after the interest for that month is covered. That lowers the balance faster, so less interest is charged the next month. Tell your lender to apply extra money to principal, not to skip ahead to next month's bill.

When is the best time to apply a lump sum?

As early as possible. A $1,000 payment at month 6 saves more than the same $1,000 at month 40, because it cuts the balance while interest charges are still large. Try different payment numbers in the Early Payoff Explorer and compare the savings.

Does the total cost include my down payment and trade-in?

Yes. Total Cost adds your down payment and trade-in value to everything you pay the lender. It shows the full value you gave up for the car. Total of Payments only counts what goes to the lender.

Does this calculator include insurance, gas, and repairs?

No. It only covers the loan, sales tax, and dealer fees. Insurance, fuel, oil changes, tires, and registration renewals are separate. Budget for those on top of the monthly payment shown here.

How close will this be to the dealer's number?

Very close if your tax rate, fee total, and APR are correct. Differences usually come from fees the dealer did not list, add-ons like warranties or gap insurance, or a rate that changes after the credit check. Always compare this figure to the signed contract.

Does choosing a credit score range change my payment?

Not by itself. The credit tier only shows the APR range buyers like you usually get. Click "Use Midpoint Rate" to drop a typical rate into the APR box, and then the results update.

Can I pay my car loan off early without a penalty?

Most auto loans in the US have no prepayment penalty, but some do. Check your contract for the words "prepayment penalty" or "precomputed interest" before you send extra money. Precomputed loans do not save you much interest when paid early.

Why did my payoff date change when I added extra payments?

Extra money cuts the balance faster, so the loan reaches zero before the last scheduled month. The amortization table shortens to match, and the New Payoff Date box shows the earlier finish month.

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