Week Number Calculator
Find the current week number and view the calendar for any date. This calculator follows the ISO 8601 standard for week numbering, where each week starts on Monday and the first week of the year contains the first Thursday.
Quick Navigation
Week Number Results
| Selected Date | - |
|---|---|
| Week Number | - |
| Week Standard | - |
| Week Range | - |
| Days Remaining in Year | - |
Calendar View
Mon
Tue
Wed
Thu
Fri
Sat
Sun
About Week Number Calculator
This Week Number Calculator helps you determine the week number for any date according to different international standards. Week numbers are commonly used in business, project planning, and various international standards.
How Week Numbers Are Calculated
The calculator supports two main week numbering systems:
- ISO 8601 Standard (International): The most widely used international standard where:
- Week starts on Monday
- First week of the year contains the first Thursday
- Week numbers range from 1 to 52 or 53
- US Standard: Commonly used in the United States where:
- Week starts on Sunday
- First week of the year contains January 1st
- Week numbers range from 1 to 52 or 53
Practical Applications
Week numbers are useful for:
- Project planning and scheduling
- Business reporting and fiscal calendars
- Academic and school schedules
- International coordination across different date formats
- Tracking recurring events that happen weekly
Interesting Facts
Some interesting aspects of week numbering:
- The ISO week numbering system can result in the first few days of January belonging to week 52 or 53 of the previous year
- Similarly, the last few days of December can belong to week 1 of the next year
- Years with 53 weeks occur approximately every 5-6 years
- Some countries (like most of Europe) commonly use week numbers in business and government documents