This calculator shows how a fixed-rate installment loan is repaid over time. Each regular payment is split between interest (the cost of borrowing) and principal (the amount you still owe). In the early months, interest takes a larger share because it’s computed on a higher balance. As the balance falls, more of each payment goes to principal, and the payoff accelerates.
The payment is based on the standard formula for a present value paid down by equal periodic payments. If P is the loan amount, i is the periodic rate (APR ÷ 12 for monthly payments), and n is the total number of months, the payment is:
Payment = P × i / (1 − (1 + i)−n) (when i = 0, Payment = P ÷ n)
Use the schedule to see the interest and principal for each period and the remaining balance after every payment. The totals summarize the dollar amount you’ll pay over the life of the loan and how much of that is interest.
- Small rate changes matter. A one-point difference in APR can add or remove thousands in interest on longer terms.
- Term length drives total interest. Shorter terms mean higher payments but a much lower interest cost.
- Extra monthly payments reduce the balance faster and shorten the term. In this tool, the extra is applied directly to principal after the regular payment.
Notes: This tool covers principal and interest only. It doesn’t model taxes, insurance, escrow, HOA dues, late fees, or prepayment penalties. Calculations are estimates and for education.
