use a week numbering system (called North American in ourCalculator) in which the first week (numbered 1) ofany given year is the week which contains January 1st. The first day of aweek is Sunday and Saturday is the last. Most of European and Asian countries use a standardized ISO 8601 week datesystem in which the week with the number 1 is the first week which containsthe first Thursday of January.In this system the first day of the week is Monday.It may happen that the first week of the year contains a few last days from theprevious year. For example， for example， 2014 (Sunday). Most Middle East countries use a calendar system (called Islamic inour Calculator) in which the week with the number 1in any given year is the one that contains January 1st. In this systemSaturday is the first day of a week and Friday is the last. How Many Weeks Are In a Year? The short answer is 52 or 53 depending on a year number.Each year contains at least 52 weeks. A quick calculation confirms that 52(weeks) times 7 days (per week) equals 364 days and there are 365 days in ayear (366 in a leap year).Existence of the 53rd week depends on a year number and the week numbering system used.Detailed information on how to calculate the number of weeks in a year can befound， Canada，。

Israel， South Korea， the first week of the 2014 starts on December30， Week Numbering Systems A week is a time unit equal to seven days.Weeks within a given year are typically numbered starting from 1.There are few week numbering systems used around the world.USA， most of Latin America。

on Wikipedia. Our Week Number Calculator can be used as a convenient tool to quicklycheck week's number and dates in one of the three numbering systems.You can easily switch between the different week numbering systems using theselect box. ， Japan。

2013 (Monday) and ends on January 5， amongothers。