Auto Loan Calculator

Monthly payment size depends more on loan term than interest rate. A $25,000 loan at 6% costs $483 monthly over 4 years but only $403 over 6 years — the extra 2 years reduces monthly burden by $80 but adds $1,900 in total interest. The calculator uses the standard amortization formula where each payment covers interest first, then principal.

The tool assumes your interest rate stays fixed for the entire loan term and that you make exactly the calculated payment each month. It does not account for gap insurance, extended warranties, or other dealer add-ons that increase the financed amount.

Down payment and trade-in value directly reduce the loan amount dollar-for-dollar. Every $1,000 in down payment typically saves $20-25 monthly depending on your rate and term, making it one of the most effective ways to control your monthly payment without extending the loan unnecessarily.

Use this calculator when you have a specific vehicle price and want to budget for monthly payments before visiting dealers. It works for both new and used car financing where you know the approximate interest rate from pre-approval or credit score research.

Do not rely on this calculator for lease payments — leasing uses residual value calculations that account for depreciation differently. It also does not apply to variable-rate loans or situations where you plan to make extra principal payments, both of which change the payment schedule from the standard amortization pattern.

Users often enter the vehicle's sticker price instead of the actual negotiated price. Sticker price includes dealer markup — using it overstates your loan amount by $2,000-5,000 on average, making payments appear higher than necessary and potentially ruling out affordable cars you could actually buy.

Another common error is forgetting to include trade-in value in the down payment field. Trade-in reduces your loan amount exactly like cash down payment, but many borrowers calculate as if they're financing the full sticker price. A $10,000 trade-in can reduce monthly payments by $200+ depending on loan terms.

Most dangerous is using dealer-quoted payment amounts without verifying the loan details. Dealers often quote payments based on longer terms or higher down payments than discussed, then present the attractive number without explaining the underlying changes that make it possible.

The monthly payment formula is M = P × [r(1+r)^n] / [(1+r)^n - 1], where M is monthly payment, P is principal (loan amount), r is monthly interest rate (APR ÷ 12), and n is total number of payments. For a $20,000 loan at 6% APR over 4 years: r = 0.06/12 = 0.005, n = 48 payments, yielding M = $469.70.

The formula calculates each payment to pay off the loan exactly on schedule. Early payments go mostly toward interest — on that $20,000 loan, the first payment includes $100 interest and $369.70 principal. By the final payment, nearly the entire amount goes to principal since little balance remains.

Zero percent financing eliminates the compound interest calculation entirely — monthly payment becomes simply loan amount divided by number of payments. A $24,000 loan over 4 years at 0% costs exactly $500 monthly with no interest charges, making promotional rates extremely valuable when available.

Auto loan rates vary significantly by loan term even with the same lender — 36-month loans often price 0.5-1% below 72-month loans because shorter terms reduce the lender's risk. Credit unions typically beat bank rates by 0.25-0.75% for auto loans, but require membership and may have limited dealer relationships for direct financing.