Week Number Calculator

Find the week number for any date with our free online calculator. Perfect for project planning, scheduling, and date calculations.

Features

• Calculate week number for any date
• Multiple week numbering systems:
  • ISO week numbers (ISO-8601)
  • Simple week numbers
• Current week number display
• Date picker interface
• Week start options:
  • Monday (ISO standard)
  • Sunday (US standard)
• Mobile-friendly interface
• No registration required

How to Use

1. Select a date using the calendar
2. Choose your preferred week numbering system
3. View the week number instantly
4. See additional date information
5. Switch between week start options

Understanding Week Numbers

ISO Week Numbers (ISO-8601)

• Weeks start on Monday
• Week 1 is the first week with 4 or more days in January
• Weeks can belong to previous/next year
• Always 52 or 53 weeks in a year

Simple Week Numbers

• Weeks start on selected day
• Week 1 starts January 1st
• All weeks belong to current year
• Usually 52 weeks, with partial weeks

Common Applications

Project Management

• Sprint planning
• Milestone tracking
• Delivery schedules
• Timeline organization

Business Planning

• Fiscal weeks
• Production schedules
• Reporting periods
• Inventory cycles

Personal Organization

• Academic planning
• Event scheduling
• Holiday planning
• Task management

Why Use Our Calculator

• Instant calculations
• Multiple systems
• Clear interface
• Works offline
• Free to use
• No ads or popups