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Car Down Payment Calculator

Enter the vehicle price, your down payment, any trade-in, the rate, and the term. The tool shows the amount financed, the monthly payment, and the total interest, then repeats the payment with the down payment doubled.

By the AutoLoanable Editorial Team · Last updated 2026-09-17

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Enter your numbers and press Calculate. Nothing you type leaves your browser.

How this calculator works

The down payment lowers the amount you finance, which lowers both the payment and the interest.

financed = price − down payment − trade-in, and payment = P × i ÷ (1 − (1 + i)^-n)

  • P — the amount financed after the down payment and trade-in
  • i — the monthly rate, the annual rate divided by 1,200
  • n — the number of monthly payments

The tool also recomputes the payment with the down payment doubled. Total interest is the payment multiplied by n minus P. A larger down payment helps, but keep an emergency fund. Enter the rate you were offered.

What changes your result

Only a few inputs move the number materially. In rough order of impact:

Sensitivity of the monthly payment
InputEffect on the paymentEffect on total cost
Amount financedDirectly proportionalDirectly proportional
Interest rate / APRDirectly proportionalDirectly proportional
Term (months)Lower payment when longerHigher total interest when longer
Down paymentLowers the paymentLowers total interest
Trade-in equityLowers the amount financedLowers total interest
Sales tax and feesRaises the amount financedRaises total cost

Enter the rate you were actually offered. This site is not a lender and does not publish rates — a quoted rate is only meaningful next to the term and the amount financed.

Frequently asked questions

How much should I put down on a car?
There is no single answer. A larger down payment lowers the amount financed and the interest, but it should not use money you need for emergencies.
Does a down payment lower the interest rate?
A down payment lowers the amount financed, which lowers the interest charged. Some lenders also view a larger down payment favourably, but the rate itself depends on your credit and the lender.
Can a trade-in replace a down payment?
A trade-in reduces the amount financed in the same way, as long as it is worth more than any loan still owed on it.
What does doubling the down payment do?
It cuts the amount financed, so the monthly payment and total interest fall. The tool shows the new payment and the interest saved.

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