Editorial policy

Where the numbers come from

For nationwide consumer-credit numbers I use the Federal Reserve G.19 release and the New York Fed's Household Debt and Credit Report. For lender-specific claims I link to the lender's own disclosure or rate page. I don't cite other personal-finance sites as a primary source — if they're right, the underlying data they used is right too, and that's what I link to.

How the calculator works

Standard amortization formula M = P · r(1+r)ⁿ / ((1+r)ⁿ − 1), calculated one month at a time and rounded to the nearest cent. Extra payments and lump sums go straight to the balance after the interest split. There's a small Vitest suite that cross-checks the math against Bankrate on a handful of reference loans.

The full math reference — formulas, cascade logic, default-value sourcing, and what the calculators don't model — lives at methodology.

Conflicts of interest

I run affiliate links to a handful of lenders. Those are listed on the disclosures page. I don't accept money to recommend a product — if I mention a specific lender it's because of their actual rates or terms at the time. If something I recommend isn't in any affiliate program I have, I'll just say so in the article.

How often this gets updated

Every page shows when it was last touched. The rate-outlook page gets refreshed around each FOMC meeting. Calculator math is essentially static — I only update if I find a bug or change a default. Lender-specific articles I try to recheck if there's been a meaningful policy change at the lender.

Corrections

If I get something wrong, email admin@payoffmath.com. Material corrections get a dated note at the bottom of the page. Typos I just fix.

What I'm not

Not a licensed financial advisor, broker, or lender. Nothing on this site is personalized advice. Talk to your loan documents and a licensed advisor before making a decision.