Week numbers 2025: all 52 ISO weeks from December to December.
2025 has 52 ISO weeks. Week 1 starts December 30, 2024, the week containing the year's first Thursday. Week 52 ends December 28, 2025. That makes it a standard 52-week year.
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.
2025 at a glance
Understanding week numbers in 2025
ISO 8601 gives every week a number from 1 to 52. 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 2024.
2025 runs the standard 52 weeks. Years only get a 53rd week when January 1 falls on a Thursday (or a leap year starting Wednesday), which is why most years stop at 52.
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 2025: questions and answers
How many weeks are in 2025?
2025 has 52 ISO weeks. It is a standard 52-week year.
When does week 1 of 2025 start?
ISO week 1 of 2025 starts on December 30, 2024 (Monday) and ends on January 5, 2025 (Sunday). It is always the week containing the first Thursday of the year.
What are the week numbers for 2025?
The week numbers for 2025 run from week 1 (starting Dec 30) through week 52 (ending December 28, 2025). This page lists all 52 weeks with their exact date ranges.
Is 2025 a 53-week year?
No, 2025 is a standard 52-week ISO year. The last week (week 52) ends on December 28, 2025.
How do I download the 2025 week number calendar?
Use the Download .ics button on this page to get a 2025 week number calendar file compatible with Google Calendar, Apple Calendar, and Microsoft Outlook. It includes all 52 ISO weeks and public holidays.