Frequently asked questions about week numbers
Does 2025 have 53 weeks?
2025 does not have a 53rd week. Because 1 January 2025 falls on a , the year contains only 52 calendar weeks according to ISO 8601.
Which years have 53 weeks?
A year is a 53-week year when 1 January is a Thursday, or a Wednesday in a leap year. Up-coming examples: .
Does week 53 always cross the new year?
Yes. For instance, week 53 of 2026 starts on 28 Dec 2026 and ends on 3 Jan 2027.
How do I use this converter?
Type the year (e.g. 2025) and the week number (e.g. 12), press “Get dates” and you will receive the Monday-Sunday calendar range immediately. Cross-year and leap-year situations are handled automatically.
In project planning, school timetables, payroll and logistics you often need to translate “week 34” into real calendar days. Our service follows the ISO 8601 definition used worldwide. You can:
- Enter any year & week number and receive the exact Monday-Sunday range;
- Browse the full 52 or 53 week list of any year and share it with one click;
- See at a glance whether a week crosses the new year or belongs to a 53-week year;
- Jump directly via URL parameters, e.g.
?year=2025&week=12.
Complementary tools: Date → Week and Today’s week number.
Pro tips
- Use the “Frequent weeks” buttons for fast access to common week numbers;
- Copy or share the result in one tap;
- Navigate quickly with the Previous / Next week buttons;
- The year overview shows every week of the chosen year in a compact grid.