All 52 ISO 8601 weeks with Monday-to-Sunday dates
The year 2021 has 52 weeks according to the ISO 8601 standard. Below is a complete list of every week with its exact Monday (start) and Sunday (end) dates. Each row links to the full week details page.
January 1, 2021 is in Week 53 of 2020. The ISO week number for Jan 1 depends on which day of the week Jan 1 falls on.
December 31, 2021 is in Week 52 of 2021.
2021 is not a leap year and has 365 days.
2021 has 52 weeks according to ISO 8601. This is the standard 52-week year length.
Week 1 of 2021 starts on January 4, 2021 and ends on January 10, 2021.
ISO 8601 week numbers are determined by the year that contains Thursday. Week 1 of 2021 is the week containing January 4, 2021. Each subsequent week is numbered sequentially.