All The Calculations

How calculator pages are built

Each calculator should answer a practical question, show how the answer was calculated, and make its assumptions clear enough that you can verify the result yourself.

Our calculator standard

  1. 01Define the question the calculator must answer in one sentence.
  2. 02Write the formula and name the inputs, units, assumptions, and edge cases.
  3. 03Add at least one worked example so the output can be checked by hand.
  4. 04Explain limitations clearly, especially for finance, construction, fitness, or safety-related estimates.
  5. 05Cite the rule, definition, or published source behind any rate, factor, or threshold.
  6. 06Keep improving pages based on questions and feedback from people who use them.

What we optimize for

  • Fast mobile use with the calculator visible right away.
  • Plain-language explanations before and after the result.
  • Stable formulas, examples, FAQs, and related calculators.
  • Clear caveats where a professional should verify the answer.
  • Pages you can cite, share, or audit later.

What we avoid

  • Publishing calculators before they are finished.
  • Hiding assumptions behind a result-only interface.
  • Making claims the page does not support.
  • Presenting estimates as financial, medical, legal, or engineering advice.

Quality checks before a page is published

  • The calculator works with realistic inputs and shows a useful result without requiring sign-up.
  • Invalid or incomplete inputs never produce a plausible-looking answer.
  • The formula, units, and assumptions are visible in plain language.
  • Examples use human situations, not just abstract variables.
  • Caveats explain when the output is only an estimate or when a professional should verify the answer.

Found a mistake or want a calculator we do not have yet? Send feedback or read more about the project.