The first Thursday decides
Week 1 is the week with the year's first Thursday, so January 1 can sit in the last week of the year before.
Week numbers 2024
Every ISO week of 2024 with its Monday and Sunday. 52 weeks in all.
Week numbers of 2024
52 weeks, each from Monday to Sunday.
Week 1
Jan 1 to Jan 7
Week 2
Jan 8 to Jan 14
Week 3
Jan 15 to Jan 21
Week 4
Jan 22 to Jan 28
Week 5
Jan 29 to Feb 4
Week 6
Feb 5 to Feb 11
Week 7
Feb 12 to Feb 18
Week 8
Feb 19 to Feb 25
Week 9
Feb 26 to Mar 3
Week 10
Mar 4 to Mar 10
Week 11
Mar 11 to Mar 17
Week 12
Mar 18 to Mar 24
Week 13
Mar 25 to Mar 31
Week 14
Apr 1 to Apr 7
Week 15
Apr 8 to Apr 14
Week 16
Apr 15 to Apr 21
Week 17
Apr 22 to Apr 28
Week 18
Apr 29 to May 5
Week 19
May 6 to May 12
Week 20
May 13 to May 19
Week 21
May 20 to May 26
Week 22
May 27 to Jun 2
Week 23
Jun 3 to Jun 9
Week 24
Jun 10 to Jun 16
Week 25
Jun 17 to Jun 23
Week 26
Jun 24 to Jun 30
Week 27
Jul 1 to Jul 7
Week 28
Jul 8 to Jul 14
Week 29
Jul 15 to Jul 21
Week 30
Jul 22 to Jul 28
Week 31
Jul 29 to Aug 4
Week 32
Aug 5 to Aug 11
Week 33
Aug 12 to Aug 18
Week 34
Aug 19 to Aug 25
Week 35
Aug 26 to Sep 1
Week 36
Sep 2 to Sep 8
Week 37
Sep 9 to Sep 15
Week 38
Sep 16 to Sep 22
Week 39
Sep 23 to Sep 29
Week 40
Sep 30 to Oct 6
Week 41
Oct 7 to Oct 13
Week 42
Oct 14 to Oct 20
Week 43
Oct 21 to Oct 27
Week 44
Oct 28 to Nov 3
Week 45
Nov 4 to Nov 10
Week 46
Nov 11 to Nov 17
Week 47
Nov 18 to Nov 24
Week 48
Nov 25 to Dec 1
Week 49
Dec 2 to Dec 8
Week 50
Dec 9 to Dec 15
Week 51
Dec 16 to Dec 22
Week 52
Dec 23 to Dec 29
How week numbers work
52 or 53 weeks
A year has 53 ISO weeks when January 1 is a Thursday, or a Wednesday in a leap year. 2024 has 52.
Why your calendar may differ
Some calendars, notably in the US, start weeks on Sunday and count the week with January 1 as week 1. That can differ from the ISO number by one.
Other years
More free tools
Frequently asked questions
Ask a questionBy ISO 8601, the standard most calendars and businesses use: a week runs from Monday to Sunday, and week 1 is the week that holds the year's first Thursday (so January 1 can be in week 52 or 53 of the year before, and December 29 to 31 can be in week 1 of the next). A year has 52 or 53 weeks.
52. A year has 53 ISO weeks when January 1 is a Thursday, or a Wednesday in a leap year.
Some calendars, notably in the US, start weeks on Sunday and count the week with January 1 as week 1. That system can differ from the ISO number by one. Check your calendar's settings: most offer ISO weeks.