What week number is it this week?
The quick answer is always in our week number tool: it shows today’s week number and converts any other date. Below you’ll learn how week numbers work and why they sometimes confuse people.
Today’s week number
At the time of writing, Tuesday 6 October 2026, it is week 41. That week runs from Monday 5 October to Sunday 11 October 2026. In the official notation it is written as 2026-W41-2: week-numbering year 2026, week 41, day 2 (Tuesday).
Reading this later? Open the week number tool. It automatically uses today’s date on your own device and shows the correct week number instantly, with the Monday and Sunday of that week.
How are week numbers defined?
Most of Europe and international business use the standard ISO 8601. It has three simple rules:
- A week starts on Monday and ends on Sunday.
- Week 1 is the week containing the first Thursday of the year. That is the same as the week containing 4 January.
- As a result, a year has 52 or 53 weeks.
Because of rule 2, the first days of January can still belong to the last week of the previous year. For example, Friday 1 January 2027 falls in week 53 of 2026. The reverse also happens: the last days of December can fall in week 1 of the next year.
Why does 2026 have 53 weeks?
A year has 53 weeks if it starts on a Thursday, or if it is a leap year starting on a Wednesday. 1 January 2026 was a Thursday, so 2026 has 53 weeks. Week 53 runs from Monday 28 December 2026 to Sunday 3 January 2027. This happens roughly once every five to six years; the last time was 2020.
US calendars count differently
In the United States and some other countries, weeks start on Sunday and week 1 is simply the week containing 1 January. That means a US calendar app or spreadsheet can show a week number that differs by one. When you work with European colleagues or suppliers, agree to use ISO week numbers, or mention the date of the Monday as well.
Week numbers in Excel, Outlook and on your phone
- Excel and Google Sheets: use
=ISOWEEKNUM(A1). The regular WEEKNUM function uses the US system by default. - Outlook and Google Calendar: turn on week numbers in the calendar settings and set Monday as the first day of the week.
- iPhone and Android: the built-in calendar apps let you enable week numbers in their settings.
Want to see the whole year at a glance? Check our overview of all week numbers in 2027.
Frequently asked questions
What week is it now?
On 6 October 2026 it is week 41. For the current week, open the week number tool, which always uses today’s date.
Does week 1 always start on 1 January?
No. Week 1 is the week with the first Thursday of the year. Week 1 of 2027 starts on Monday 4 January 2027.
How many weeks are in 2026?
2026 has 53 weeks, because the year started on a Thursday.