About Payoff Logic
Payoff Logic exists for one reason: most free financial calculators are either too shallow to be useful or buried under pop-ups and lead forms. We build calculators that show the complete math — full amortization schedules, every component of a mortgage payment, real side-by-side comparisons — with no account, no download, and no sales pitch.
Who's behind this site
Payoff Logic is built, tested, and edited by Thanakorn Praisee, an independent developer and personal-finance writer. Thanakorn builds every calculator on this site from the underlying loan math — amortization, payoff formulas, and government-program rules — and verifies each one against published reference examples before it ships (the process is documented in our editorial policy). The guides are written the same way: every figure in them is computed by the same tested engines that power the tools, not copied from other sites.
We are independent: Payoff Logic is not a lender, broker, or financial advisory firm, and no bank or lender pays to influence our results or content. Thanakorn is not a licensed financial advisor — which is exactly why this site sticks to what can be verified: the math. What a loan costs, when PMI cancels, how a payoff date moves — these have exact answers, and the site's job is to show them transparently.
How we keep the math honest
- Every calculator is verified against known-correct reference examples before launch, and the test cases are documented.
- Reference data (such as state property-tax rates or average home values) is cited to its source on the page where it appears, and we record when it was last reviewed.
- When we find an error, we fix it and note the correction — accuracy matters more than looking infallible.
The full detail is in our Editorial Policy & Methodology, and every dataset we prefill is cited on our Data Sources page.
How the site makes money
The calculators are free and always will be. The site is supported by display advertising and, in some cases, affiliate links that are clearly marked. Advertisers never see the numbers you enter and never influence calculator results.
What we are not
We are not financial advisors, and nothing on this site is financial, legal, or tax advice. Our tools help you understand the math behind a decision; the decision itself should factor in your full situation — ideally with a qualified professional. See our Terms of Use for details.
Get in touch
Found a bug, a math error, or have a calculator you wish existed? We read everything — contact us.