About Calcora

Calcora is a free, multilingual reference for conversions, exchange rates, world time and everyday calculations – built to give the right answer first, with the method and sources right underneath.

Accuracy first

Every unit conversion uses exact definitions from NIST Special Publication 811, NIST Handbook 44 (Appendix C) and the BIPM SI Brochure (9th edition). Values are computed directly from these definitions, never typed in by hand, and rounded only for display.

The formula is shown on every page so that anyone can verify a result.

Data sources

Exchange rates: euro foreign exchange reference rates of the European Central Bank (ECB), published on TARGET business days around 16:00 CET. Cross rates are derived through the euro.

Time zones: the IANA Time Zone Database used by modern operating systems and browsers. Sunrise and sunset: the NOAA solar position algorithms.

Calculators: standard financial and health formulas (annuity formula, compound interest, WHO BMI categories).

Always up to date

The site is regenerated automatically every day. New exchange rates, daylight saving changes and sun times appear without manual work, and an automated quality check blocks any release with broken pages or links.

Pages are continuously refined using aggregated, anonymous search data – for example, the values people look up most often are added to the conversion tables.

Languages

All pages are available in English, Japanese, Spanish, Portuguese, German, French, Italian and Indonesian, with localized number formats and unit names.

Contact

Found an error or have a suggestion? Please use the contact page – corrections are reviewed promptly.