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Week Number
Find the current ISO 8601 week number, look up the week number of any date, and browse every week of the year with its start and end dates.
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Week number of any date
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About Week Number
Week numbers follow the international ISO 8601 standard: weeks run Monday to Sunday, and week 1 is the week containing the year's first Thursday. Because of that rule, a year has either 52 or 53 numbered weeks, and the last days of December can belong to week 1 of the next year. Week numbers are the everyday language of planning across much of Europe — this page shows the current week live, converts any date to its week, and lists every week of the year.