Week numbers for 2021
View all week numbers for 2021 in the table below. Each week shows its start and end date according to the ISO 8601 standard.
| Week Numbers 2021: | Start date: | End date: |
|---|---|---|
| week 1 | 01/04/2021 | 01/10/2021 |
| week 2 | 01/11/2021 | 01/17/2021 |
| week 3 | 01/18/2021 | 01/24/2021 |
| week 4 | 01/25/2021 | 01/31/2021 |
| week 5 | 02/01/2021 | 02/07/2021 |
| week 6 | 02/08/2021 | 02/14/2021 |
| week 7 | 02/15/2021 | 02/21/2021 |
| week 8 | 02/22/2021 | 02/28/2021 |
| week 9 | 03/01/2021 | 03/07/2021 |
| week 10 | 03/08/2021 | 03/14/2021 |
| week 11 | 03/15/2021 | 03/21/2021 |
| week 12 | 03/22/2021 | 03/28/2021 |
| week 13 | 03/29/2021 | 04/04/2021 |
| week 14 | 04/05/2021 | 04/11/2021 |
| week 15 | 04/12/2021 | 04/18/2021 |
| week 16 | 04/19/2021 | 04/25/2021 |
| week 17 | 04/26/2021 | 05/02/2021 |
| week 18 | 05/03/2021 | 05/09/2021 |
| week 19 | 05/10/2021 | 05/16/2021 |
| week 20 | 05/17/2021 | 05/23/2021 |
| week 21 | 05/24/2021 | 05/30/2021 |
| week 22 | 05/31/2021 | 06/06/2021 |
| week 23 | 06/07/2021 | 06/13/2021 |
| week 24 | 06/14/2021 | 06/20/2021 |
| week 25 | 06/21/2021 | 06/27/2021 |
| week 26 | 06/28/2021 | 07/04/2021 |
| week 27 | 07/05/2021 | 07/11/2021 |
| week 28 | 07/12/2021 | 07/18/2021 |
| week 29 | 07/19/2021 | 07/25/2021 |
| week 30 | 07/26/2021 | 08/01/2021 |
| week 31 | 08/02/2021 | 08/08/2021 |
| week 32 | 08/09/2021 | 08/15/2021 |
| week 33 | 08/16/2021 | 08/22/2021 |
| week 34 | 08/23/2021 | 08/29/2021 |
| week 35 | 08/30/2021 | 09/05/2021 |
| week 36 | 09/06/2021 | 09/12/2021 |
| week 37 | 09/13/2021 | 09/19/2021 |
| week 38 | 09/20/2021 | 09/26/2021 |
| week 39 | 09/27/2021 | 10/03/2021 |
| week 40 | 10/04/2021 | 10/10/2021 |
| week 41 | 10/11/2021 | 10/17/2021 |
| week 42 | 10/18/2021 | 10/24/2021 |
| week 43 | 10/25/2021 | 10/31/2021 |
| week 44 | 11/01/2021 | 11/07/2021 |
| week 45 | 11/08/2021 | 11/14/2021 |
| week 46 | 11/15/2021 | 11/21/2021 |
| week 47 | 11/22/2021 | 11/28/2021 |
| week 48 | 11/29/2021 | 12/05/2021 |
| week 49 | 12/06/2021 | 12/12/2021 |
| week 50 | 12/13/2021 | 12/19/2021 |
| week 51 | 12/20/2021 | 12/26/2021 |
| week 52 | 12/27/2021 | 01/02/2022 |
What is a week number?
A week number is the sequential number assigned to each week in a calendar year. We use the ISO 8601 international standard, where each week begins on Monday and runs through Sunday.
Calendar with week numbers
The calendar consists of 12 months. To reference smaller time periods, week numbers provide a convenient solution. Many activities are scheduled for a specific week when an exact date isn't yet confirmed. Week numbers offer a practical way to communicate these timeframes.
Week numbers for 2021
Week numbers on the calendar help make scheduling clearer. Week 1 begins in the first full week of January, following the ISO 8601 standard used internationally for business and planning.
The current week number is determined by the date. January 4 always falls in the first week of the year - this is the standard rule. Because of this, February 1 always falls in week 5.
You can calculate the current week number yourself by counting the elapsed weeks or checking a calendar. However, this is time-consuming, which is why we provide a complete overview for each year showing all week numbers with their start and end dates.
What is the week number this week?
Week numbers are particularly important for maintaining organized schedules and coordinating with others. Our tools make it easy to track week numbers throughout the year.
FAQ
How many weeks are in 2021?
The year 2021 has 52 weeks. This is determined by the ISO 8601 standard where week 1 is the first week with at least 4 days in January.
When does week 1 of 2021 start?
Week 1 of 2021 begins on the Monday closest to January 1, as long as at least 4 days fall in January.
How are week numbers determined?
We use the ISO 8601 international standard. Each week starts on Monday, and week 1 is the first week with at least 4 days in the new year. This means January 4 always falls in week 1.
See also: Calendar 2021