About Weeknumber.io

Weeknumber.io is a focused utility for answering week-number questions without requiring an account. The site is free to use and is funded by ads from Google AdSense; see the privacy policy. The site uses ISO 8601 as its default because it defines Monday-first weeks and a consistent week-year rule.

What we publish

We publish calculators, complete year tables, accessible calendars, printable files and short task-focused guides. We do not publish automated pages for every individual week.

Editorial approach

Explanations are kept close to the task they support. Claims about calendar products or spreadsheet functions link to primary documentation where practical.