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Look up week numbers under ISO 8601, the US Standard, and the Australian Financial Year — accurate to the second, switchable on the fly.
1 Jan 2024 - 8 Jan 2024
Year: 2024
Reference
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.
Read the ISO 8601 referenceUnited States
Sunday-start weeks; week 1 contains 1 January. Default in Microsoft Excel WEEKNUM and most US payroll systems.
Read the US Standard referenceAustralia
Week numbering anchored to 1 July, the start of the Australian financial year. Used by the ATO, BAS quarters, and Australian businesses.
Read the AU Financial Year referenceQuick lookups
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Open the full year calendar or browse the reference articles to understand how each standard calculates weeks.