Calendar by week number 2015 iso#
Thus, if a Gregorian year contains 52 Thursdays then the corresponding ISO calendar year has 52 weeks and if the Gregorian year containsĥ3 Thursdays then the corresponding ISO calendar year has 53 weeks. Examples of these extreme cases in the recent past are December 2014Īs Thursday is the middle day of the ISO week, each Thursday in a Gregorian calendar year belongs to the same ISO calendar year.
![calendar by week number 2015 calendar by week number 2015](https://thumbs.dreamstime.com/b/vector-calendar-week-starts-sunday-31713731.jpg)
![calendar by week number 2015 calendar by week number 2015](https://www.wheniscalendars.com/wp-content/uploads/2018/12/12-month-calendar-2019-MoWnoMon-1-6_Page_05.png)
Likewise, the last week of the ISO calendar year can end as early as 28 December and as late as 3 January Likewise, the last week of the ISO calendar year is the last week that contains at least four days of the month of December.Īccording to this rule the first week of the ISO calendar year can begin as late as 4 January and as early as 29 December The numbering of the ISO calendar weeks is defined (sect. 2.2.10 on p. 5) as: the first calendar week of a year is that one which includes the first Thursday of that yearĪnd the last calendar week of a calendar year is the week immediately preceding the first calendar week of the next calendarĪnother way of stating the above rule is that the first week of the ISO calendar year is the earliest week that contains at least four days The week in the ISO calendar is defined (sect. 2.2.8 on p. 5) as a: time interval of seven calendar days starting with a Monday identified by its ordinal number On average, however, it remains in step with the Gregorian calendar. The ISO calendar corresponds with the Gregorian calendar (sect. 3.2.1 on pp. 7-8) and uses the same year number but as its length isĭefined to be an integral number of weeks, its beginning can deviate up to a few days from 1 January and its end likewise can deviate up toĪ few days from 31 December. The calendar defined in the ISO standards 20 is commonly Repealed on 1 June 1988 with the imminent introduction of ISO 8601. This week numbering scheme was introduced earlier by the ISO with the standard ISO 2015:1976 ( Numbering of Weeks) and was In iOS however, week 01 starts on Monday, Decem(provided that you have set Monday as the first day of a week in your settings).Mathematics of the ISO 8601 Calendar - The ISO Calendar The ISO 8601 Calendar If 1 January is on a Friday, it is part of week 53 of the previous year if on a Saturday, it is part of week 52 (or 53 if the previous year was a leap year) if on a Sunday, it is part of week 52 of the previous year.įurther more, if you search Google for "week number", at least the top 5 results follows the above ISO standard.įollowing this ISO standard, week 01 of 2016 starts on Monday, January 4 2016. If 1 January is on a Monday, Tuesday, Wednesday or Thursday, it is in week 01. It has the year's first working day in it, if Saturdays, Sundays and 1 January are not working days.Hence the earliest possible dates are 29 December through 4 January, the latest 4 through 10 January. Its first day is the Monday nearest to 1 January.It is the first week with a majority (4 or more) of its days in January.The following definitions based on properties of this week are mutually equivalent, since the ISO week starts with Monday: The ISO 8601 definition for week 01 is the week with the year's first Thursday in it. The next years that will have 53 weeks based on the ISO week date standard are 2020, 2026, and 2032.Īlthough there might be several ways to determine week numbers, the by far most widely used is the one specified by ISO 8601 (International Organization for Standardization). From what I understand this only happens about once every 11 years so Apple putting too much into making a change that would be implemented in 2016 probably isn't very high.Įdit: I was wrong on the every 11 years. You can submit feedback to but they would need to have a lot of people request it and then wait for Apple to actually implement it in a future release. Unfortunately there isn't a way to change which method you use in iOS.
![calendar by week number 2015 calendar by week number 2015](https://www.wheniscalendars.com/wp-content/uploads/2020/05/2021-printable-calendar-holidays-yearly-wk-bah-4.png)
The method that you are referring to considers week 1 to be the week containing January 4th or the first Tuesday of the month. This method is used by Apple, Microsoft (confirmed in Outlook), and even sites like and apps like Calendars 5. This is regardless of whether or not January 1st is on the first day of the week, the middle of the week, or the last day of the week. The basic method is that week 1 is the week that has January 1st. There are multiple systems for numbering weeks.