Loan Calculator

A loan calculator answers the question every borrower actually cares about: given a principal, an interest rate, and a term, what's the fixed monthly payment, and where does all that money actually go? This tool takes a loan amount, an annual interest rate, and a term in years and months, and works out the standard fixed monthly payment using the same amortization formula banks and lenders use for mortgages, auto loans, personal loans, and student loans.

The formula behind it is M = P × [r(1 + r)ⁿ] ÷ [(1 + r)ⁿ − 1], where M is the monthly payment, P is the principal, r is the monthly interest rate (the annual rate divided by 12 and by 100), and n is the total number of monthly payments (years × 12, plus any extra months). When the rate is exactly 0%, the formula simplifies to just the principal divided evenly across the number of payments, since there's no interest to amortize.

Beyond the monthly payment figure, this tool builds a full month-by-month amortization schedule showing, for every single payment, exactly how much goes toward interest versus principal, and what the remaining balance is afterward. Early payments on a loan are interest-heavy: most of the payment just covers interest on the still-large balance, while later payments are almost entirely principal, since the balance (and therefore the interest charged on it) has shrunk. A stacked chart above the table visualizes this shift in real time as you adjust the loan's terms, making it easy to see exactly how much total interest a loan actually costs over its full term versus how much of it is principal being paid back.

Every figure and every row of the schedule updates live as you type or adjust the term, with no "Calculate" button to press. Every calculation runs as plain JavaScript directly in your browser, so nothing about your loan is ever sent to a server, logged, or stored anywhere.