Week Number Calculator
Find the week number of any date in different formats
Week Number Calculator
Standard Week Range
Feb 23 - Mar 01, 2025
ISO Week Range
Feb 24 - Mar 02, 2025
Week Numbers
Calculate standard and ISO week numbers for any date
Multiple Formats
View week numbers in different standard formats
Week Ranges
Get the start and end dates for each week
About Week Number Calculator: Guide to Week Numbering Systems
The Week Number Calculator helps you determine the exact week number for any date using different week numbering systems. Whether you're planning projects, analyzing data, or managing schedules, this tool provides accurate week calculations.
Understanding Week Numbers
- Standard Week Number: Weeks numbered from 1-53, starting from the first week of the year
- ISO Week Number: International standard where weeks start on Monday and the first week contains January 4th
- Week of Month: The week's position within its month, useful for monthly planning
Common Use Cases
Business Planning
- Sprint planning
- Financial reporting
- Project scheduling
- Resource allocation
Data Analysis
- Weekly reporting
- Trend analysis
- Performance tracking
- Data aggregation
Pro Tips for Week Number Calculations
- ISO vs Standard: Use ISO week numbers for international business to ensure consistency
- Week Ranges: Consider week ranges for accurate period planning
- Month Weeks: Use week of month for month-based planning cycles
FAQs
What's the difference between standard and ISO weeks?
ISO weeks always start on Monday and are standardized internationally. The first ISO week of the year contains January 4th, while standard weeks can vary by region and system.
How are week numbers calculated?
Week numbers are calculated based on the day of the year and specific rules for each system. The calculator handles these complexities automatically, including year transitions.
Why do some years have 53 weeks?
Years can have 53 weeks when December 31st falls on a Thursday (or Wednesday in leap years), pushing the last few days into an additional week.