About Payment Calculator

Payment Calculator is a set of free, browser-based borrowing calculators (mortgage, home affordability, refinance, general loan, auto loan, and credit card payoff) built and maintained by Joe Koppin, a software engineer. The goal was a calculator that shows the full picture, a complete amortization schedule and a real payment breakdown, without an account, a paywall, or a slow, ad-choked page in the way of a number you need right now.

Every calculation here runs entirely client-side. No accounts, no backend processing your numbers, no database. That's not a marketing claim, it's a consequence of what this site actually is: a static export with no server-side application logic at all. What you enter into a calculator, home price, loan amount, interest rate, is processed by JavaScript running in your own browser and goes nowhere else. See the Privacy Policy for the specifics.

Beyond the calculators themselves, the Guides section covers the concepts behind the numbers in more depth: why early loan payments are mostly interest, what actually separates APR from the interest rate, what makes up a full mortgage payment, how much house an income supports, when refinancing pays off, and how credit card interest compounds, for when the calculator result raises a question the number alone doesn't answer. The calculators and guides are both educational tools, meant to help you understand the math; they aren't financial advice, and nothing here is a recommendation about what loan, rate, or lender to choose. For decisions specific to your situation, talk to a qualified financial or mortgage professional.

Payment Calculator is part of the Ten Eleven family of free, no-signup web tools. The site is free to use and ad-supported. If a calculator saved you time, a coffee is always appreciated but never required. Questions, bug reports, or a calculator you'd like to see added can go to privacy@paymentcalculatoronline.com.