About Notes Online

This site exists for one job — a notes online that gives a clear answer quickly and shows how it was reached.

Testing before every update

Every release of the notes online is checked by an automated test suite of 169 checks in a real browser — normal values, edge cases and invalid input — and on desktop and phone screen sizes before it goes live.

References

The formulas and reference values in the guides follow published standards and primary sources, linked where they are used: developer.mozilla.org.

Our approach

Pages are written and maintained by the site's editorial team. We aim to answer the question people actually ask, show worked examples with real numbers, and say plainly where a calculator cannot replace professional advice. Nothing on this site is sponsored content.

Updates and corrections

First published October 8, 2026; last updated October 12, 2026. If you spot an error or a case the tool handles badly, please tell us through the contact page — corrections are reviewed and published in the next update.

Advertising

The tool is free to use. The site is funded by advertising, which never influences results or explanations.

— Notes Online editorial team