About Calculate7

Calculate7 is a growing collection of single-purpose calculators covering math, finance, health, conversion, physics, chemistry, biology, and construction. Each calculator is a standalone tool — pick the one you need, get an answer in seconds, and read the worked-out explanation if you want to understand how it got there.

Every calculator includes the formulas being used, worked examples, edge cases to watch for, and citations to the standards bodies that publish the underlying definitions (NIST, IUPAC, CDC, IRC, BIPM, and others). We surface the math instead of hiding it — if you don't trust the result, you can verify it.

The site is published in five languages: English (default), Spanish, German, French, and Brazilian Portuguese. Each calculator is fully translated, with units and conventions adapted where appropriate (decimal commas vs decimal points, metric vs imperial defaults, etc.).

Calculator math is easy to get wrong. We've focused on a few things to keep it right:

• Exact constants over approximations. We use 1 inch = 2.54 cm exactly, IUPAC 2021 atomic weights, and the CODATA values for physical constants — never the school-textbook approximations that introduce 1–2% error.
• Edge cases handled explicitly. Things like "what happens when the rounding pushes an inch to 12" or "what if the user enters 0" are tested, not assumed.
• Sources are cited on every calculator. If you click into a calculator, the bottom of the page lists where its formulas, reference tables, and standard values come from — with links to the authoritative source.
• Translations don't change the math. The numbers and units shown in Spanish or German are exactly what the English calculator shows, just localized. Decimal commas, but identical precision.

If you find an inaccuracy, please tell us — we publish corrections promptly.

Calculate7 is funded entirely by display advertising through Google AdSense. We don't take paid placements, sponsored content, or affiliate commissions on the calculators themselves — ads are clearly separated from the calculator results, and no calculator's output is influenced by an advertiser.

This funding model lets us keep every calculator free with no signup, no paywall, and no premium tier. If you'd like to support the site without using it, the most helpful thing is to allow ads (we keep ad density reasonable) and share calculators you find useful.

We've tried to build the site in a way that respects your time and your data:

• No accounts. You never need to sign up to use a calculator.
• Calculations stay in your browser. Inputs you type into a calculator are processed locally — they don't get sent to our servers, and we don't store them.
• Cookies are limited. We use cookies only for site analytics (understanding which pages are popular) and for ads (Google AdSense). See our privacy policy for the full list.
• Open standards. The site is plain HTML + JavaScript, no frameworks that need consent prompts beyond the analytics/ads cookies. It works without third-party cookies.

For corrections, calculator suggestions, partnership inquiries, or anything else, see our contact page. We typically respond within a few business days.

For legal questions, see our terms of service and disclaimer. The disclaimer is especially important for the health, finance, and construction calculators — those are useful for estimates, but they're not a substitute for talking to a professional.