What This Calculator Does
The Loan Payment After Down Payment Calculator shows your fixed monthly payment on the amount you actually finance — the purchase price minus your down payment. It works for car loans, equipment financing, personal loans, and any fixed-rate installment loan. Because a larger down payment reduces the principal, it directly lowers both your monthly payment and the total interest you pay over the life of the loan.
How to Use It
Enter the full purchase price, the cash you plan to put down, the annual interest rate (APR), and the loan term in years. The calculator subtracts the down payment to find the financed principal, then applies the standard amortization formula to return your monthly payment, the total of all payments, and the total interest cost.
The Formula Explained
First the principal is computed: \(P = \text{Price} - \text{Down Payment}\). Then the monthly payment is found with the amortization formula
$$M = P \cdot \frac{r}{1 - (1+r)^{-n}}$$where \(r\) is the monthly interest rate (annual rate ÷ 12 ÷ 100) and \(n\) is the total number of monthly payments (years × 12). If the rate is 0%, the payment is simply the principal divided by the number of months.
Worked Example
Suppose you buy a $30,000 car with a $5,000 down payment at 6% APR over 5 years. The financed principal is $25,000. The monthly rate is \(0.06 \div 12 = 0.005\) and \(n = 60\). The payment is
$$25{,}000 \times \frac{0.005}{1 - 1.005^{-60}} \approx \$483.32$$Over 60 months you pay about $28,999.20 total, of which roughly $3,999.20 is interest.
FAQ
Does a bigger down payment always help? Yes — it lowers the financed principal, so both your monthly payment and total interest fall.
Are taxes and fees included? No. Enter the price you are financing; add taxes or fees to the price field if they are rolled into the loan.
What rate should I enter? Use the loan's nominal annual percentage rate (APR). The tool converts it to a monthly rate for you.
