What week of the year is it?

Our week number calculator shows the current week number based on ISO 8601 standard. The week number updates automatically as the year progresses.

How many weeks are in a year?

Most years have 52 weeks, but some years have 53 weeks. A year has 53 weeks if January 1 falls on a Thursday, or on Wednesday in a leap year.

How do I calculate the week number?

The ISO week number is calculated based on the Thursday of each week. Week 1 is the week containing the first Thursday of the year.

What is ISO week numbering?

ISO 8601 is the international standard for week numbering. Weeks start on Monday, and Week 1 is the week with the year's first Thursday. This system is used in most of Europe and many businesses worldwide.

Does every year have 52 weeks?

No, some years have 53 weeks. This happens approximately every 5-6 years when the year starts on a Thursday (or Wednesday in leap years).

When does week 1 start?

In ISO standard, Week 1 is the week containing January 4th, or equivalently, the week with the first Thursday of the year. This means Week 1 can start in late December of the previous year.

📆 Week Number Calculator

Find the ISO week number for any date

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Current Year Week Overview

Week	Start Date	End Date

What is ISO Week Number?

The ISO week number is a standard way to identify weeks within a year. According to ISO 8601:

Weeks start on Monday and end on Sunday
Week 1 is the week containing the first Thursday of the year
A year can have 52 or 53 weeks
The last days of December may belong to week 1 of the next year

ISO week numbers are widely used in business, project management, and international scheduling.