Quick answer (as of November 14, 2026)
- Today is in week 46 of 2026 (ISO 8601).
- Week 46 runs from Monday, November 9, 2026 to Sunday, November 15, 2026.
- 2026 has 53 weeks. Weeks start on Monday; week 1 is the week with the year’s first Thursday.
ISO week numbers in short
The international standard ISO 8601 numbers weeks from Monday to Sunday. Week 1 is the week that contains the year’s first Thursday, which is the same as saying the week that contains January 4. A year therefore has 52 or 53 weeks, and the first days of January can belong to the last week of the previous year.
US week numbers vs. ISO week numbers
Many US calendars and planners start the week on Sunday and call the week that contains January 1 “week 1”. That system and the ISO system often differ by one week, which causes mix-ups between US offices and teams in Europe or Asia that plan by ISO weeks.
| ISO 8601 | Common US style | |
|---|---|---|
| Week starts on | Monday | Sunday |
| Week 1 is | the week with the first Thursday | the week with January 1 |
| Jan 1, 2027 is in | week 53 of 2026 | week 1 of 2027 |
| Excel / Google Sheets | =ISOWEEKNUM(date) | =WEEKNUM(date) |
How to use the week tool
- The current week number and its Monday–Sunday dates are shown at the top.
- Pick any date to see which week it falls in.
- Enter a week number and year to get its start and end dates.
- Scroll the table to see every week of the year at once.
Frequently asked questions
What week is it now?
The number at the top of the page is today’s ISO week, worked out from your device’s date.
Does 2026 have 53 weeks?
Yes. 2026 starts on a Thursday, so it gets a 53rd ISO week, which runs from December 28, 2026 to January 3, 2027.
Why does Excel show a different week number?
WEEKNUM uses the US style by default (Sunday start, January 1 in week 1). Use ISOWEEKNUM for ISO weeks.
When does week 1 of 2027 start?
Monday, January 4, 2027.
Every date, offset and calculation on this page was checked against the sources below.