About AmortGrid
What AmortGrid is
AmortGrid is an independent suite of 27 free mortgage, loan and debt calculators. It spans four core financial pillars: mortgages and home equity (standard payments, full amortisation schedules, biweekly payments, adjustable-rate mortgages, balloon payments, recast, extra payments, affordability, closing costs, points, PMI, HELOC and rent vs. buy); government-backed lending (FHA and VA loans); consumer credit (auto loans, student loans and personal loans); and debt elimination strategies (debt payoff, debt consolidation, credit card payoff and compound interest growth). Every calculator runs locally in your browser: you enter your numbers, the page derives the instalment, the lifetime interest and the period-by-period schedule, and nothing is ever transmitted to a server.
Who it is for
AmortGrid is for anyone in the United States or the United Kingdom who needs a straight answer about borrowing. That includes first-time buyers working out what they can afford, homeowners deciding whether to overpay or refinance, borrowers comparing a 15-year term against a 30-year term, and anyone who wants to check a lender's or broker's figures before signing. You do not need an account, an email address or any financial documents to use it.
Why we built it
A mortgage is usually the largest financial commitment a household ever makes, yet the tools people use to understand it are often slow, crowded with advertising, or unwilling to explain where their numbers come from. We wanted the opposite: a calculator suite that loads quickly, works on a phone, explains its assumptions in plain English, and treats your financial information as yours rather than ours.
How we work & Editorial Standards
Every formula adheres to established United States regulatory standards, including Consumer Financial Protection Bureau (CFPB) guidelines under Regulation Z (Truth in Lending Act) and standard actuarial conventions. Each calculation is implemented once in a unified financial math engine, covered by an automated unit test suite that asserts every published figure against the live calculation engine. Reference scenarios (such as a $300,000 loan at 6.5% over 30 years producing a monthly payment of $1,896.20) are asserted on every build.
We publish our method openly. The methodology page sets out the amortisation formula and the meaning of every symbol, the nominal-rate convention and why we use it, how extra payments are applied, the affordability ratios, the rounding policy, the testing policy and what our models deliberately do not attempt to predict. Because results are computed client-side, the amounts you type in never leave your device.
AmortGrid is independent. We are not owned by, funded by or operated on behalf of a bank, mortgage lender, broker or lead-generation network. No lender reviews our calculations, and no commercial partner decides what our guides say.
Our principles
- One formula, one implementation. Each calculation is written once and covered by tests, so a fix in one place fixes every calculator.
- Publish the method. The formula, the rate convention, the assumptions and the known limitations are written down for anyone to check.
- Your inputs stay yours. Calculations happen in your browser. We do not transmit, store or sell the amounts, income or debts you enter.
- No account, no paywall. No sign-up and no email address are required to see a result.
- Independence. Advertising and affiliate relationships never change a calculation, a result or the wording of a guide, and any commercial relationship is disclosed where it appears.
- Corrections come first. A report that a figure is wrong takes priority over everything else in our queue.
What we do not do
We do not give financial advice, and we do not arrange, broker, originate or sell loans. The calculators produce estimates from the figures you supply. Our disclaimer and terms of service explain the limits of the site, and the contact page explains how to tell us when a number looks wrong.
Last reviewed 2026-10-11.