Our Methodology
Who maintains this site
Calculator.uk.com is built and maintained by the calculator.uk.com team. We're a small, independent operation focused on one thing: free calculators that give correct answers, with the reasoning behind each one shown rather than hidden.
How we source formulas
Cited sources per calculator
Every calculator on this site includes a "What is the scientific source for this calculator?" answer in its FAQ section, naming the specific methodology, academic literature, professional guidelines, or industry/regulatory standard the calculation is based on — for example HMRC guidance for UK tax calculators, or published engineering and scientific standards for technical ones. We don't link out to third-party sites from calculator pages, but the source is always named in the text.
Verification before publishing
Before a calculator is published, we check its output against known reference cases and test edge cases (zero values, negative inputs, unusually large numbers) to confirm the formula is implemented correctly, not just theoretically correct.
Review practice
Calculators are reviewed on a rolling basis rather than all at once — the "last reviewed" date shown on each page reflects that. A review covers whether the formula, thresholds, or rates a calculator relies on are still current (tax bands and regulatory figures change periodically, for example) and whether the explanation is still accurate.
Limitations
Our calculators are general-purpose tools, not personalized advice. Results — particularly for financial, medical, or veterinary calculators — should be treated as estimates and are not a substitute for advice from a qualified professional. Formulas and figures can go out of date between reviews; always confirm current rates or guidelines for decisions that matter.
Found an error?
If a calculator gives a result that looks wrong, or a cited source is out of date, we want to know. Reach out through the details on our Legal page and we'll review it.