What week is it? Today is…

This week in every format

Different teams write the same week different ways. All of these refer to the current week:

More on where each style comes from in the week number formats guide, or convert any date with the week number calculator.

How week numbers work

The week number tells you where you are in the year, counted in weeks instead of days or months. WeekYear uses ISO 8601, the international standard: weeks run Monday to Sunday, and week 1 is the week containing January 4 — equivalently, the week with the year's first Thursday. That rule means the first days of January can still belong to the last week of the previous year (and late December days can belong to week 1 of the next year), which keeps every week exactly seven days with a single, unambiguous number.

Because 365 days ÷ 7 leaves one day over, a year always has 52 full weeks plus one or two days. Most years therefore have 52 numbered weeks, and roughly every 5–6 years the alignment produces a week 53. If you plan payroll, sprints, or budgets by week, those 53-week years matter — see the 53-week payroll year and how many weeks in a year.

Not everyone counts the same way: the US convention starts weeks on Sunday and calls the week with January 1 "week 1", which can put its number one ahead of the ISO number. If a week number from a colleague or an app looks off by one, that's almost always why — week start conventions explains the differences and this guide shows how to turn week numbers on in Google, Outlook, and Apple calendars.