Week Number Calculator · Live

What week number
is it today?

Look up week numbers under ISO 8601, the US Standard, and the Australian Financial Year — accurate to the second, switchable on the fly.

LiveISO 8601

Current week

Standard

Reference

Three week-numbering standards

Most of the world's calendars run on one of three rules. Choose the one your business or software follows.

International

The international standard. Monday-start weeks; week 1 contains the first Thursday of the year. Used in software, finance, and European business.

United States

Sunday-start weeks; week 1 contains 1 January. Default in Microsoft Excel WEEKNUM and most US payroll systems.

Australia

Week numbering anchored to 1 July, the start of the Australian financial year. Used by the ATO, BAS quarters, and Australian businesses.

Quick lookups

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Open the full year calendar or browse the reference articles to understand how each standard calculates weeks.