Current week number

How week numbers work (ISO 8601)

Week numbers follow the international ISO 8601 standard: weeks start on Monday, and week 1 is the week that contains the first Thursday of January — equivalently, the week of January 4. That's why a year has 52 weeks in most years and 53 in some (like 2026), and why the last days of December can already belong to week 1 of the next year.

The United States and a few other countries traditionally count differently (weeks starting Sunday, week 1 containing January 1), so calendars can disagree by one. Business, logistics and schools in Europe use the ISO numbers shown here.