Loan Payment Formula
A fixed-payment loan uses loan amount, periodic interest rate, and number of payments to estimate the monthly payment.
Core formula
Payment = P * r * (1 + r)^n / ((1 + r)^n - 1)
P is loan principal, r is monthly interest rate, and n is total number of payments.
Answer summary
Use the calculator to compare monthly payment, total repayment, and total interest as the term or rate changes.
Related: ROI formula, inflation guide.
Quick worksheet before using the calculator
Use this short worksheet to keep the page useful before you open the live calculator. Enter a rough amount, a rate or percentage, and a time period, then use the button as a deliberate step into the calculator rather than clicking away to an unrelated destination.
Before relying on a result, compare at least two scenarios: conservative, expected, and optimistic. For financial planning, the calculator is a planning aid, not tax, lending, or investment advice.