Week numbers 2021: all 52 ISO weeks from January to January.
2021 has 52 ISO weeks. Week 1 starts January 4, 2021, the week containing the year's first Thursday. Week 52 ends January 2, 2022. That makes it a standard 52-week year.
The table below lists every week with its Monday start and Sunday end date, plus public holidays for the US, UK, Canada and Australia. Click any week for full details, or download the whole year as an .ics file. Looking for a single week? Jump to this week's number, or check how ISO week numbering works.
| Week | From (Mon) | To (Sun) | Month | Q | Public holidays & events | |
|---|---|---|---|---|---|---|
| Q1 · 2021 | ||||||
| 1 | Jan | Q1 | details → | |||
| 2 | Jan | Q1 | details → | |||
| 3 | Jan | Q1 | details → | |||
| 4 | Jan | Q1 | details → | |||
| 5 | Feb | Q1 | details → | |||
| 6 | Feb | Q1 | Valentine's Day | details → | ||
| 7 | Feb | Q1 | Family Day (ON, AB, BC, SK) | details → | ||
| 8 | Feb | Q1 | details → | |||
| 9 | Mar | Q1 | details → | |||
| 10 | Mar | Q1 | International Women's Day | details → | ||
| 11 | Mar | Q1 | Spring Equinox (Vernal) | details → | ||
| 12 | Mar | Q1 | details → | |||
| Q2 · 2021 | ||||||
| 13 | Mar | Q2 | Good Friday Easter Sunday Good Friday | details → | ||
| 14 | Apr | Q2 | Easter Monday | details → | ||
| 15 | Apr | Q2 | details → | |||
| 16 | Apr | Q2 | Earth Day | details → | ||
| 17 | Apr | Q2 | details → | |||
| 18 | May | Q2 | details → | |||
| 19 | May | Q2 | details → | |||
| 20 | May | Q2 | details → | |||
| 21 | May | Q2 | Victoria Day | details → | ||
| 22 | May | Q2 | details → | |||
| 23 | Jun | Q2 | details → | |||
| 24 | Jun | Q2 | details → | |||
| 25 | Jun | Q2 | Summer Solstice | details → | ||
| Q3 · 2021 | ||||||
| 26 | Jun | Q3 | Canada Day | details → | ||
| 27 | Jul | Q3 | details → | |||
| 28 | Jul | Q3 | details → | |||
| 29 | Jul | Q3 | details → | |||
| 30 | Jul | Q3 | details → | |||
| 31 | Aug | Q3 | Civic Holiday (ON/AB) | details → | ||
| 32 | Aug | Q3 | details → | |||
| 33 | Aug | Q3 | details → | |||
| 34 | Aug | Q3 | details → | |||
| 35 | Aug | Q3 | details → | |||
| 36 | Sep | Q3 | Labour Day | details → | ||
| 37 | Sep | Q3 | details → | |||
| 38 | Sep | Q3 | Autumn Equinox | details → | ||
| 39 | Sep | Q3 | National Day for Truth and Reconciliation | details → | ||
| Q4 · 2021 | ||||||
| 40 | Oct | Q4 | details → | |||
| 41 | Oct | Q4 | Thanksgiving (Canada) | details → | ||
| 42 | Oct | Q4 | details → | |||
| 43 | Oct | Q4 | Halloween | details → | ||
| 44 | Nov | Q4 | details → | |||
| 45 | Nov | Q4 | Remembrance Day | details → | ||
| 46 | Nov | Q4 | details → | |||
| 47 | Nov | Q4 | details → | |||
| 48 | Nov | Q4 | details → | |||
| 49 | Dec | Q4 | details → | |||
| 50 | Dec | Q4 | details → | |||
| 51 | Dec | Q4 | Christmas Day Boxing Day | details → | ||
| 52 | Dec | Q4 | New Year's Day | details → | ||
2021 at a glance
Understanding week numbers in 2021
ISO 8601 gives every week a number from 1 to 52. Each week runs Monday to Sunday, and week 1 is the one holding the year's first Thursday. So if January starts late in the week, those early January days belong to the last week of 2020.
2021 runs the standard 52 weeks. Years only get a 53rd week when January 1 falls on a Thursday (or a leap year starting Wednesday), which is why most years stop at 52.
Want a single week instead of the full year? Each row links to its own detail page. Need to convert a date? The week calculator handles that. And the weeks in a year guide explains 52 versus 53 in depth.
Week calendars for other years
Week numbers 2021: questions and answers
How many weeks are in 2021?
2021 has 52 ISO weeks. It is a standard 52-week year.
When does week 1 of 2021 start?
ISO week 1 of 2021 starts on January 4, 2021 (Monday) and ends on January 10, 2021 (Sunday). It is always the week containing the first Thursday of the year.
What are the week numbers for 2021?
The week numbers for 2021 run from week 1 (starting Jan 4) through week 52 (ending January 2, 2022). This page lists all 52 weeks with their exact date ranges.
Is 2021 a 53-week year?
No, 2021 is a standard 52-week ISO year. The last week (week 52) ends on January 2, 2022.
How do I download the 2021 week number calendar?
Use the Download .ics button on this page to get a 2021 week number calendar file compatible with Google Calendar, Apple Calendar, and Microsoft Outlook. It includes all 52 ISO weeks and public holidays.