Editorial Policy

All financial math on this site — every calculator and every figure quoted in an article — comes from a single calculation engine covered by automated unit tests. No formula lives only in prose or in a spreadsheet. This means a calculator and the guide describing it can't disagree: they call the same code, and that code has tests that fail if it changes unexpectedly.

Before a worked example is published, its numbers are cross-checked against the engine's automated tests. The published examples are the same scenarios the test suite asserts on — so if the engine ever changes in a way that would make a published example stale, a test fails and the example gets updated before anything ships.

Calculator defaults are typical, clearly-labeled, editable starting points — never live market quotes. Each default is documented with its rationale on the methodology page, and every calculator tells you to replace defaults with the actual figures from your quote. When we describe a value as "typical," that claim links back to the methodology rather than standing on its own.

Content pages carry a visible "Last updated" date. Those dates are maintained in a single source file — not typed by hand into each page — so a page can't claim to be fresher than it is, and a substantive update can't ship without its date moving.

If you believe any published number is wrong, email hello@leasevsbuycar.com with a link to the page. Correction reports get priority over all other mail. Here is what happens next:

1. We reproduce the number against the calculation engine and its tests.
2. If it's wrong, we fix the page (and, if the engine itself is at fault, the engine and its tests).
3. The page's "Last updated" date is bumped, so the correction is visible.

See the contact page for response-time expectations.

The site is supported by advertising, disclosed on the about page. Ads are visually distinct from content, never appear inside a calculator or its results, and advertisers have no access to, or influence over, what we publish or what the calculators return.