Editorial policy

What we publish

We publish a calculator only when it answers a real question better than a quick sum on paper: clearer inputs, the working shown, and an explanation of what the result means. We don't publish near-duplicate pages for every variation of a query. One strong calculator that handles the variations is more useful.

How a calculator is published

1. Formula. The formula and assumptions are written down and checked against a primary source where one exists.
2. Tests. Automated tests cover typical, edge-case and invalid inputs.
3. Content. The explanation, assumptions and FAQs are written to match exactly what the calculator does.
4. Review. Before publishing, a second pass checks accuracy, clarity and links.
5. Quality checks. Automated checks look for broken links, duplicate titles or descriptions, missing headings and invalid structured data.

Dates on pages

The "updated" date on a page changes only when its content or formula actually changes. We don't refresh dates to make pages look newer. A "reviewed" date and reviewer name appear only when a named person has actually reviewed the page.

Sources

For finance, health, legal or scientific topics, we cite primary or authoritative sources, such as government agencies, regulators, standards bodies and academic publications. We list the date each source was last checked.

Use of AI

We may use AI writing tools to help draft or edit explanations. Every published page is checked by a person for accuracy and usefulness. AI is never used to calculate results: every result comes from tested, deterministic code.

Independence

Calculators aren't designed to steer you toward a product. If we ever show advertising, it will be clearly labelled and kept away from calculator inputs and results.

Corrections

Report errors through the contact page. We fix confirmed errors promptly. When a correction changes a formula, we update the version number shown on the calculator.