📅 Calendar week number

Week counting depends on the time zone chosen in the time settings of your device!

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A week is a time unit equal to seven days. It is the standard time period used for cycles of rest days in most parts of the world, mostly alongside the Gregorian calendar. Weeks in a Gregorian calendar year can be numbered for each year. This style of numbering is commonly in some European and Asian countries, but rare elsewhere.

The calendar year consists of at least 52 weeks, which are numbered as calendar weeks, especially in business life. There are various definitions of week numbering. Depending on the rule applied, the first week of a year can be determined differently.

Calculation in Europe, Asia and Oceania

EU and most of other European countries, most of Asia and Oceania use the ISO-8601 System. ISO 8601 includes the ISO week date system, a numbering system for weeks. Each week begins on a Monday and is associated with the year that contains that week's Thursday.

Calculation in the USA and many other countries

In many parts of the world (e.g. North America, Australia) the Judeo-Christian tradition of counting Sunday as the first day of the week has been preserved. In the USA and countries that also use the scheme valid there, the following rule applies: Every Sunday a new calendar week begins and on 1 January the first calendar week starts. The first and last calendar week of a year need not be complete and may contain less than seven days. Each year that is not a leap year or whose 31 December is not a Sunday has 53 calendar weeks. If December 31 of a leap year is a Sunday, then that Sunday is the only day in the 54th calendar week (this case occurs relatively rarely: last in the year 2000, next time in 2028). In US business life and in public communication there, however, calendar weeks in the form of consecutive numbers as above are rarely used. Instead, a week is usually designated by its Monday, e.g. "week of June 20".