Find Week of Year - Calculate What Week of Year a Date Falls On

Our free online find week of year tool calculates what week of the year (1-52/53) any date falls on. Whether you need to know the week number for business reporting, project planning, or academic purposes, this tool provides instant calculation with multiple week systems and comprehensive date information.

How to Use the Find Week of Year Tool

Enter Date: Input date in ISO (2024-01-15), US (01/15/2024), EU (15/01/2024), or Full format
Choose Week System: Select from ISO 8601, US System, or January 1st System
Select Output Format: Choose from Number, Ordinal, Percentage, Fraction, or All Formats
Include Additional Info: Optionally include extra date information like percentage of year, weeks remaining, etc.
Get Result: View the week of year with comprehensive date analysis

Week Systems Explained

ISO 8601: Monday is the first day of the week, week 1 is the first week with at least 4 days in the new year
US System: Sunday is the first day of the week, week 1 starts on January 1st
January 1st System: Week 1 starts on January 1st regardless of the day of week

Output Formats Explained

Number: Simple number (1-52/53)
Ordinal: Ordinal format (1st, 2nd, 3rd, etc.)
Percentage: Percentage of year completed
Fraction: Decimal fraction of year (0.000000-0.999999)
All Formats: Combination of all formats

Additional Information Provided

Year: The year of the date
Month: Full month name
Day: Day of the month
Day of Year: Which day of the year (1-365/366)
Week of Year: Which week of the year (1-52/53)
Is Leap Year: Whether the year is a leap year
Weeks Remaining: How many weeks left in the year
Percentage Completed: What percentage of the year has passed
Percentage Remaining: What percentage of the year is left
Quarter: Which quarter of the year (Q1-Q4)

Use Cases for Finding Week of Year

Business Reporting: Weekly reports and analytics
Project Management: Track project progress by weeks
Academic Planning: Semester and academic year planning
Financial Planning: Weekly budget and expense tracking
Event Planning: Schedule events by week
Data Analysis: Time series and temporal analysis
International Business: Coordinate across different week systems

Week System Differences

Different week systems can give different results for the same date:

ISO 8601: Most internationally recognized, used in Europe and many countries
US System: Common in the United States, Sunday-based weeks
January 1st System: Simple system where week 1 always starts on January 1st

Date Format Support

ISO Format: 2024-01-15 (YYYY-MM-DD)
US Format: 01/15/2024 (MM/DD/YYYY)
EU Format: 15/01/2024 (DD/MM/YYYY)
Full Format: January 15, 2024

Frequently Asked Questions

How is week of year calculated?

Week of year is calculated differently depending on the system chosen. ISO 8601 uses Monday as the first day of the week and week 1 is the first week with at least 4 days in the new year. US system uses Sunday as the first day and week 1 starts on January 1st. January 1st system always starts week 1 on January 1st regardless of the day.

What's the difference between ISO 8601 and US week systems?

ISO 8601 uses Monday as the first day of the week and week 1 is the first week with at least 4 days in the new year. US system uses Sunday as the first day of the week and week 1 always starts on January 1st. This can result in different week numbers for the same date.

Why are there 53 weeks in some years?

Some years have 53 weeks instead of 52 because the year doesn't divide evenly into 7-day weeks. This happens when January 1st falls on certain days of the week, creating an extra week at the end of the year. The tool automatically handles this calculation.

Which week system should I use?

Use ISO 8601 for international business and most European countries. Use US system for United States-based applications. Use January 1st system for simple calculations where you need consistent week numbering. The choice depends on your specific requirements and regional standards.

Can I use this tool for business reporting?

Yes, the tool is perfect for business reporting, project management, and financial planning. It provides multiple week systems to match your organization's standards and includes additional information like percentage of year completed and weeks remaining for comprehensive analysis.

How accurate is the week calculation?

The calculation is very accurate and follows international standards. ISO 8601 calculations are based on the official ISO 8601 standard, US system follows common US business practices, and January 1st system provides a simple, consistent approach for basic calculations.