Loan / Mortgage Calculator computes your fixed monthly payment, total interest, and full month-by-month amortization schedule from a loan amount, annual interest rate, and term in years. Each row of the schedule shows exactly how much of that month's payment goes toward principal versus interest, and what balance remains afterward — the same breakdown you'd see on a lender's official amortization table.

The full schedule can be exported as a CSV file for use in a spreadsheet, with a row count and totals that match what's shown on screen. Every calculation happens locally; no loan details are ever sent to a server.

Behind the scenes this uses the standard fixed-rate amortization formula — M = P × r(1+r)ⁿ / ((1+r)ⁿ − 1), where P is the loan principal,r is the interest rate per month, and n is the total number of monthly payments — the same formula lenders use to compute the fixed payment on a traditional mortgage or auto loan. Because the payment is fixed but the balance shrinks every month, the split between principal and interest shifts over the life of the loan: early payments are mostly interest (since the balance, and therefore the interest owed on it, is still large), while later payments are mostly principal — a pattern often called "front-loaded interest" that surprises people the first time they see their own amortization schedule laid out month by month.

A 0% interest rate is handled as a special case — dividing by r in the standard formula is undefined when r is zero, so the calculator falls back to splitting the principal evenly across the term instead, which is mathematically what a 0% loan actually is: no interest, just principal divided by the number of payments. This schedule models a standard fixed payment with no extra principal contributions; if you make additional payments toward principal in real life, your actual payoff will be faster and your total interest lower than what's shown here.