Editorial Policy

How calculators are built and tested

1. Standard formulas only. Every tool implements published, conventional mathematics — never proprietary shortcuts. The exact formula behind each calculator is documented on our methodology page.
2. Verification before publication. Each calculator is checked against worked examples from authoritative sources (textbook annuity tables, HMRC VAT examples, WHO BMI references) before going live. The test cases we used are published so you can re-run them yourself.
3. Full-precision computation. We round only for display, never mid-calculation, and we document our rounding rules.
4. Privacy by architecture. Calculations run entirely in your browser. We never see, transmit, or store the numbers you enter.

How written content is produced

• Guides and explanations are written to answer the question a reader actually has, with worked numerical examples rather than abstractions.
• Factual claims about tax rates, thresholds, health guidance, and exchange rates are sourced from primary authorities (HMRC, WHO/NHS, central banks) and linked where cited.
• Every page shows a "last reviewed" date. When external facts change — for example, tax thresholds at the start of a new tax year — affected pages are updated and the date refreshed.
• We write in plain language. If a technical term is unavoidable, we define it where it first appears.

Corrections

We treat accuracy reports as the highest-priority feedback we receive. If you believe any result or statement on this site is wrong, contact us with the details. Our process:

1. We reproduce the issue with your inputs.
2. If confirmed, we fix it and update the page's "last reviewed" date.
3. For material errors (a wrong formula or wrong factual claim, as opposed to a typo), we note the correction on the affected page.

Advertising and independence

• This site is funded by advertising (Google AdSense). Ads are clearly distinguishable from content and tools.
• Advertisers have no influence on calculator results, content, or recommendations. No calculator output is ever altered, weighted, or framed to favour a commercial partner.
• We do not publish sponsored content presented as editorial. If that ever changes, sponsored material will be explicitly labelled.
• We do not sell personal data, and calculations never leave your device. See our privacy policy.

What this site is not

Our calculators produce mathematical estimates for general information. They are not financial, medical, tax, or legal advice, and they cannot account for your personal circumstances. For decisions that matter — taking a loan, managing your health, filing taxes — verify the numbers with the relevant provider or a qualified professional. Our terms of use set this out formally.

Who is responsible

The Online Calculator is maintained by a small independent team. Editorial responsibility for everything published on this site rests with the site operator, reachable at contact@the-online-calculator.com. More about us on the about page.