Editorial policy & methodology

People make real decisions with our numbers, so we hold them to a high standard. This page explains how.

How calculators are built

• All math lives in one shared calculation engine using exact decimal arithmetic (not floating point), rounded to the cent the way lenders round.
• Each calculator has automated tests: hand-checked "golden" examples plus property tests that check rules like "a larger down payment never raises the payment".
• A release can't go live unless every test passes.
• Every result lists its assumptions. Each calculator shows a version number, and we change it when the method changes.

Data sources

We prefer primary, official sources: the US Census Bureau (for example, American Community Survey property tax and home value data), HUD for FHA rules, and the Department of Veterans Affairs for VA funding fees. Every dataset records its source, year and method. When we couldn't yet confirm a figure against the official publication, we label it as needing verification and fix it as soon as we can.

Our property tax by state data is published with a free CSV download.

Example rates

Where a page needs an interest rate for an example, we use a stated example rate rather than claiming a live market rate. Your lender's Loan Estimate is the source of truth for your own loan.

AI answers

Our AI assistant may only use our calculators as tools. It doesn't calculate numbers itself, it's instructed to stay within personal-finance topics, and it doesn't give personalized financial advice.

Independence

If we show advertising or partner offers in the future, they will be clearly labeled and kept separate from results. No partner can pay to change a calculation, an assumption or a ranking.

Corrections

If you think a number is wrong, email [email protected] with the page and inputs. We investigate every report, fix confirmed errors quickly and update the calculator version.