Car Auto Loan Amortization Table Calculator

This car auto loan amortization table calculator estimates your monthly payment and total interest from the loan amount, annual percentage rate (APR), and term. It also explains how each payment is divided between interest and principal, so you can understand how the balance changes over time.

Formula

The calculator uses the standard fixed-payment loan formula. It first finds the monthly payment, then estimates total interest by subtracting the amount borrowed from all scheduled payments:

• Monthly payment: M = P × r ÷ [1 − (1 + r)⁻ⁿ]
• Total interest: I = M × n − P

Here, P is the loan amount in dollars, r is the monthly interest rate as a decimal, calculated as APR ÷ 1,200, n is the number of monthly payments, calculated as years × 12, and M is the monthly payment in dollars. The APR is entered as a percentage per year; for example, 8 means 8%, not 0.08. The displayed payment is rounded to the nearest cent, and total interest uses that rounded payment.

Worked Example

Using the calculator’s defaults—$20,000 borrowed at 8% APR for five years:

1. Convert the APR to a monthly decimal rate: 8 ÷ 1,200 = 0.0066667.
2. Convert the term to payments: 5 × 12 = 60 months.
3. Substitute into the payment formula: M = 20,000 × 0.0066667 ÷ [1 − (1 + 0.0066667)⁻⁶⁰].
4. The monthly payment rounds to $405.53.
5. Total scheduled payments are $405.53 × 60 = $24,331.80. Estimated total interest is $24,331.80 − $20,000 = $4,331.80.

These are the calculator’s two results for the defaults. A lender’s actual payment schedule can differ if its payment dates, rounding, fees, or loan structure differ.

Assumptions

• The interest rate is fixed for the full term.
• Payments are equal monthly payments, made at the end of each monthly period.
• Interest accrues monthly using APR divided by 12.
• The calculation excludes fees, taxes, insurance, optional products, and any down payment or trade-in unless those amounts are already reflected in the loan amount.

How an Auto Loan Amortization Table Works

An amortization table, sometimes called an amortization schedule, lays out each scheduled payment and the resulting balance. At the start of the loan, the balance is largest, so a larger part of a level payment generally goes to interest. As principal is paid down, interest charged for later periods falls, and more of the same payment goes toward principal.

For each month, the basic schedule calculates interest as the opening balance multiplied by the monthly rate. The principal portion is the payment minus that month’s interest. Subtracting principal from the opening balance gives the closing balance, which becomes the next month’s opening balance. Small differences in a lender’s schedule can arise because the lender may calculate interest using actual calendar days or apply its own rounding conventions.

This page returns payment and total interest, not a month-by-month table. To build a schedule manually, repeat the monthly calculation above for every payment period, using the prior closing balance as the next opening balance. The final payment may need adjustment by a few cents to bring the balance exactly to zero.

How to Use the Estimate

Enter the amount financed, not necessarily the car’s advertised price. The financed amount can reflect a down payment or trade-in and may also include other amounts if they are part of the loan agreement. Enter the APR and term shown in the lender’s disclosure or quote; the sample 8% rate is only a calculator default, not a claim about available rates.

• Loan amount: Use the principal actually being financed.
• APR: Enter the annual percentage as a number, such as 8 for 8%.
• Term: Enter the number of years. The calculator converts years to monthly payments.

Use the payment result to understand the formula’s scheduled monthly amount, and the interest result to see the modeled cost of borrowing over the full term. These figures are not a budget or an approval estimate. Check the lender’s itemized figures for the payment due date, any amount due at signing, and charges that are not represented by the three inputs.

Common Misunderstandings and Limits

A common mistake is treating APR as the monthly rate. The formula divides APR by 1,200 because APR is entered as a percentage per year and payments are monthly. Another is assuming that the vehicle price is the loan principal: the amount financed can be different, so use the documented principal for a closer calculation.

The formula models a conventional loan with a fixed rate and regular level payments. It does not model a changing rate, irregular payment dates, skipped or late payments, extra principal payments, a balloon payment, or a final residual balance. It also does not add separate charges or estimate the effect of a product included in a contract. For a loan with extra payments, the balance would generally fall faster, and total interest would need to be recalculated using the actual payment schedule.

Displayed values are rounded to cents. Multiplying the displayed monthly payment by the number of payments may therefore differ slightly from totals calculated internally with unrounded values; this calculator explicitly uses the rounded payment for its total-interest result. A lender may use a different rounding or accrual method.

Frequently Asked Questions

What is an auto loan amortization table?
An auto loan amortization table is a period-by-period record showing each payment, its interest and principal portions, and the remaining loan balance.

How do I calculate the monthly car payment?
Convert APR to a monthly decimal by dividing by 1,200, convert the term to months, and use the fixed-payment formula shown above with the amount financed.

Why does the interest portion change each month?
Monthly interest is calculated on the outstanding balance. As the balance declines, the interest portion generally declines and the principal portion of a level payment increases.

Does this calculator include a down payment or trade-in?
No separate field is provided. Enter the resulting amount financed after accounting for any down payment or trade-in, if applicable.

Can I use this estimate for extra payments?
Not directly. The calculation assumes equal scheduled payments and does not account for additional principal payments. A schedule with extra payments requires recalculating the balance period by period.

This result is an estimate, and the lender’s disclosure gives the exact figures.

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in p | Loan amount | $ | 20000 | 1 | 100000000
in apr | Interest rate (APR) | % | 8 | 0.01 | 100
in yrs | Loan term | years | 5 | 0.0833 | 50
out pmt | Monthly payment | $ | p * (apr / 1200) / (1 - (1 + apr / 1200) ^ -(yrs * 12)) | 2
out int | Total interest | $ | pmt * yrs * 12 - p | 2