Week numbers 2026: all 53 ISO weeks from December to January.
2026 has 53 ISO weeks. Week 1 starts December 29, 2025, the week containing the year's first Thursday. Week 53 ends January 3, 2027. Because January 1, 2026 sits early in the week, this is a 53-week year, one more than the usual 52.
The table below lists every week with its Monday start and Sunday end date, plus public holidays for the US, UK, Canada and Australia. Click any week for full details, or download the whole year as an .ics file. Looking for a single week? Jump to this week's number, or check how ISO week numbering works.
2026 at a glance
Understanding week numbers in 2026
ISO 8601 gives every week a number from 1 to 53. Each week runs Monday to Sunday, and week 1 is the one holding the year's first Thursday. So if January starts late in the week, those early January days belong to the last week of 2025.
2026 is one of the rare 53-week years. That happens when the year has enough days to push a full extra week onto the calendar. The next 53-week years don't come often, so it's worth noting if you plan payroll or reporting around week numbers.
Want a single week instead of the full year? Each row links to its own detail page. Need to convert a date? The week calculator handles that. And the weeks in a year guide explains 52 versus 53 in depth.
Week calendars for other years
Week numbers 2026: questions and answers
How many weeks are in 2026?
2026 has 53 ISO weeks. It is a 53-week year because January 1, 2026 falls on a Thursday, meaning the last ISO week of the year extends into early January of the following year.
When does week 1 of 2026 start?
ISO week 1 of 2026 starts on December 29, 2025 (Monday) and ends on January 4, 2026 (Sunday). It is always the week containing the first Thursday of the year.
What are the week numbers for 2026?
The week numbers for 2026 run from week 1 (starting Dec 29) through week 53 (ending January 3, 2027). This page lists all 53 weeks with their exact date ranges.
Is 2026 a 53-week year?
Yes, 2026 is a 53-week ISO year. The extra week 53 runs from December 28, 2026 to January 3, 2027.
How do I download the 2026 week number calendar?
Use the Download .ics button on this page to get a 2026 week number calendar file compatible with Google Calendar, Apple Calendar, and Microsoft Outlook. It includes all 53 ISO weeks and public holidays.