ISO Week Number

ISO week numbers provide a standardized way to refer to weeks throughout the year. This system is widely used in international business, logistics, manufacturing, and project management.

Key rules of ISO week numbering: - Weeks start on Monday and end on Sunday - Week 1 is the week containing the first Thursday of the year - A year has either 52 or 53 weeks - Days in early January might belong to week 52 or 53 of the previous year - Days in late December might belong to week 1 of the next year

This means that January 1 is not always in week 1. If January 1 falls on a Friday, Saturday, or Sunday, it belongs to the last week of the previous year.

ISO week numbers are particularly useful for: - International shipping and logistics - Manufacturing schedules - Financial reporting - Project planning across regions - Comparing data across years

The system ensures consistency across countries and eliminates confusion about when weeks start.