Auto Loan Calculator — Monthly Car Payment & Total Cost
Enter the vehicle price, down payment, trade-in value, sales-tax rate, APR, and loan term to get your monthly payment, total interest paid, and a full amortisation picture of how the loan balance shrinks each month.
%
%
Loan term
Fixed monthly installment for the loan term
500.95
/monthPrincipal
71.3%
Interest
14.4%
Down payment
14.3%
- 1
Loan principal
30,000 − 5,000 = 25,000 - 2
Monthly interest rate (r)
7.5% ÷ 12 ÷ 100 = 0.00625 - 3
Growth factor (1+r)ⁿ
1.00625ⁿ = 1.4533 - 4
Monthly payment
25,000 × 0.00625 × 1.4533 ÷ (1.4533 − 1) = 500.95
How does this calculator work?
Monthly payment = P × r(1+r)^n / [(1+r)^n − 1], where P is the loan amount (price + tax − down − trade-in), r is the monthly rate (APR ÷ 12), and n is the term in months. Total cost = monthly payment × n + down payment. Longer terms reduce monthly payments but increase total interest paid significantly.
Formula
How this is calculated
An auto loan is a simple amortising instalment loan: you borrow the vehicle's price minus your down payment and trade-in (plus any sales tax rolled into the loan), then repay in equal monthly instalments over the chosen term. Each payment covers that month's interest on the outstanding balance plus a slice of principal — as the balance shrinks, a growing fraction of each payment goes to principal rather than interest.
Sales-tax rates on vehicle purchases vary widely by US state (0% to about 10%) and by country. Enter your local rate to see the true loan amount; leave it at 0 if tax is paid separately or is not applicable. APR (Annual Percentage Rate) is the annualised cost of the loan; divide by 12 to get the monthly rate used in the formula. Figures here use 2025 typical US dealer APR ranges (roughly 5%–14% for new vehicles, higher for used) as a reference — always verify with your actual lender offer.
Longer loan terms lower monthly payments but increase total interest paid significantly. A 60-month loan at 7.5% versus 36 months on the same principal costs roughly 40% more in interest total. The donut chart and balance curve help visualise this trade-off.
Frequently asked questions
As of 2025, US new-car APRs range from roughly 5%–7% for excellent credit (720+), 7%–10% for good credit (660–720), and 12%–20%+ for subprime. Used-car loans typically run 2–5 percentage points higher. Credit unions often offer rates 1–3 points below dealership financing. Always shop multiple lenders before accepting the dealer's rate.
A larger down payment reduces the principal, cutting both monthly payment and total interest — and it lowers the risk of being 'upside-down' (owing more than the car is worth). A common rule of thumb is 20% down for new vehicles and 10% for used, though anything above zero helps.
Shorter terms (24–36 months) mean higher monthly payments but far less total interest and faster equity build-up. Longer terms (72–84 months) cut the monthly payment but cost significantly more in interest and extend the period during which you may owe more than the car is worth. Most financial planners recommend staying under 60 months for used cars and 72 for new.
TG we-Calculate Editorial Team. (2026). Auto Loan Calculator — Monthly Car Payment & Total Cost [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/auto-loan-calculator
TG we-Calculate Editorial Team. "Auto Loan Calculator — Monthly Car Payment & Total Cost." TG we-Calculate. 2026. https://we-calculate.com/calculator/auto-loan-calculator.
TG we-Calculate Editorial Team, "Auto Loan Calculator — Monthly Car Payment & Total Cost," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/auto-loan-calculator
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