Week Numbers 2023
2023 has 52 numbered weeks under ISO 8601 and 53 under the US convention. Week 1 starts on Monday 2 January 2023 and week 52 ends on Sunday 31 December 2023.
Today in UTC.
Weeks run Monday to Sunday. Week 1 holds the first Thursday.
Week number now
of 52 in 2023 · ISO 8601 numbering
Wednesday 4 January 2023 is in week 1 of 2023 under ISO 8601 numbering. That week runs from Monday 2 January 2023 to Sunday 8 January 2023.
Both conventions agree on this date: week 1 either way. They part company for most of January and often at the end of December.
Show the working
| Date | 2023-01-04 |
|---|---|
| Weekday | Wednesday |
| ISO week 1 starts | 2023-01-02 |
| US week 1 starts | 2023-01-01 |
| This week runs | 2023-01-02 to 2023-01-08 |
| Weeks in 2023 | 52 weeks |
Every week of 2023
ISO 8601 weeks, running Monday to Sunday. Week 1 is the week holding the first Thursday of the year, which is why it can start in the previous December.
| Week | Starts | Ends | ISO dates |
|---|---|---|---|
| Week 1 | 2 January 2023 | 8 January 2023 | 2023-01-02 to 2023-01-08 |
| Week 2 | 9 January 2023 | 15 January 2023 | 2023-01-09 to 2023-01-15 |
| Week 3 | 16 January 2023 | 22 January 2023 | 2023-01-16 to 2023-01-22 |
| Week 4 | 23 January 2023 | 29 January 2023 | 2023-01-23 to 2023-01-29 |
| Week 5 | 30 January 2023 | 5 February 2023 | 2023-01-30 to 2023-02-05 |
| Week 6 | 6 February 2023 | 12 February 2023 | 2023-02-06 to 2023-02-12 |
| Week 7 | 13 February 2023 | 19 February 2023 | 2023-02-13 to 2023-02-19 |
| Week 8 | 20 February 2023 | 26 February 2023 | 2023-02-20 to 2023-02-26 |
| Week 9 | 27 February 2023 | 5 March 2023 | 2023-02-27 to 2023-03-05 |
| Week 10 | 6 March 2023 | 12 March 2023 | 2023-03-06 to 2023-03-12 |
| Week 11 | 13 March 2023 | 19 March 2023 | 2023-03-13 to 2023-03-19 |
| Week 12 | 20 March 2023 | 26 March 2023 | 2023-03-20 to 2023-03-26 |
| Week 13 | 27 March 2023 | 2 April 2023 | 2023-03-27 to 2023-04-02 |
| Week 14 | 3 April 2023 | 9 April 2023 | 2023-04-03 to 2023-04-09 |
| Week 15 | 10 April 2023 | 16 April 2023 | 2023-04-10 to 2023-04-16 |
| Week 16 | 17 April 2023 | 23 April 2023 | 2023-04-17 to 2023-04-23 |
| Week 17 | 24 April 2023 | 30 April 2023 | 2023-04-24 to 2023-04-30 |
| Week 18 | 1 May 2023 | 7 May 2023 | 2023-05-01 to 2023-05-07 |
| Week 19 | 8 May 2023 | 14 May 2023 | 2023-05-08 to 2023-05-14 |
| Week 20 | 15 May 2023 | 21 May 2023 | 2023-05-15 to 2023-05-21 |
| Week 21 | 22 May 2023 | 28 May 2023 | 2023-05-22 to 2023-05-28 |
| Week 22 | 29 May 2023 | 4 June 2023 | 2023-05-29 to 2023-06-04 |
| Week 23 | 5 June 2023 | 11 June 2023 | 2023-06-05 to 2023-06-11 |
| Week 24 | 12 June 2023 | 18 June 2023 | 2023-06-12 to 2023-06-18 |
| Week 25 | 19 June 2023 | 25 June 2023 | 2023-06-19 to 2023-06-25 |
| Week 26 | 26 June 2023 | 2 July 2023 | 2023-06-26 to 2023-07-02 |
| Week 27 | 3 July 2023 | 9 July 2023 | 2023-07-03 to 2023-07-09 |
| Week 28 | 10 July 2023 | 16 July 2023 | 2023-07-10 to 2023-07-16 |
| Week 29 | 17 July 2023 | 23 July 2023 | 2023-07-17 to 2023-07-23 |
| Week 30 | 24 July 2023 | 30 July 2023 | 2023-07-24 to 2023-07-30 |
| Week 31 | 31 July 2023 | 6 August 2023 | 2023-07-31 to 2023-08-06 |
| Week 32 | 7 August 2023 | 13 August 2023 | 2023-08-07 to 2023-08-13 |
| Week 33 | 14 August 2023 | 20 August 2023 | 2023-08-14 to 2023-08-20 |
| Week 34 | 21 August 2023 | 27 August 2023 | 2023-08-21 to 2023-08-27 |
| Week 35 | 28 August 2023 | 3 September 2023 | 2023-08-28 to 2023-09-03 |
| Week 36 | 4 September 2023 | 10 September 2023 | 2023-09-04 to 2023-09-10 |
| Week 37 | 11 September 2023 | 17 September 2023 | 2023-09-11 to 2023-09-17 |
| Week 38 | 18 September 2023 | 24 September 2023 | 2023-09-18 to 2023-09-24 |
| Week 39 | 25 September 2023 | 1 October 2023 | 2023-09-25 to 2023-10-01 |
| Week 40 | 2 October 2023 | 8 October 2023 | 2023-10-02 to 2023-10-08 |
| Week 41 | 9 October 2023 | 15 October 2023 | 2023-10-09 to 2023-10-15 |
| Week 42 | 16 October 2023 | 22 October 2023 | 2023-10-16 to 2023-10-22 |
| Week 43 | 23 October 2023 | 29 October 2023 | 2023-10-23 to 2023-10-29 |
| Week 44 | 30 October 2023 | 5 November 2023 | 2023-10-30 to 2023-11-05 |
| Week 45 | 6 November 2023 | 12 November 2023 | 2023-11-06 to 2023-11-12 |
| Week 46 | 13 November 2023 | 19 November 2023 | 2023-11-13 to 2023-11-19 |
| Week 47 | 20 November 2023 | 26 November 2023 | 2023-11-20 to 2023-11-26 |
| Week 48 | 27 November 2023 | 3 December 2023 | 2023-11-27 to 2023-12-03 |
| Week 49 | 4 December 2023 | 10 December 2023 | 2023-12-04 to 2023-12-10 |
| Week 50 | 11 December 2023 | 17 December 2023 | 2023-12-11 to 2023-12-17 |
| Week 51 | 18 December 2023 | 24 December 2023 | 2023-12-18 to 2023-12-24 |
| Week 52 | 25 December 2023 | 31 December 2023 | 2023-12-25 to 2023-12-31 |
2023 at a glance
| ISO 8601 weeks | 52 |
|---|---|
| US weeks | 53 |
| Days in the year | 365 |
| Leap year | No |
| 1 January falls on | Sunday |
| 31 December falls on | Sunday |
Why the first week can start in December
Week 1 of 2023 starts on Monday 2 January 2023. If that date is in December it is not a mistake. ISO 8601 assigns a whole week to the year holding most of its days, so a week straddling New Year belongs to one year or the other rather than being split in half.
The same rule at the other end means the last days of 2023 can fall in week 1 of 2024. Both are correct, and both are shown by the tool above when you enter a date near the boundary.
Frequently asked questions
How many weeks are in 2023?
52 under ISO 8601 numbering, and 53 under the US convention. 2023 is a common year of 365 days, which is 52 weeks and one day over.
When does week 1 of 2023 start?
Monday 2 January 2023 under ISO 8601, which runs Monday to Sunday. Under the US convention it starts on Sunday 1 January 2023. Both can begin in the previous December, which is normal.
Does 2023 have 53 weeks?
No. 2023 has 52 ISO weeks. A year only has 53 when it starts on a Thursday, or on a Wednesday in a leap year, and 1 January 2023 is a Sunday.