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 2028
Every ISO week of 2028 with its Monday and Sunday. 52 weeks in all.
Week numbers of 2028
52 weeks, each from Monday to Sunday.
Week 1
Jan 3 to Jan 9
Week 2
Jan 10 to Jan 16
Week 3
Jan 17 to Jan 23
Week 4
Jan 24 to Jan 30
Week 5
Jan 31 to Feb 6
Week 6
Feb 7 to Feb 13
Week 7
Feb 14 to Feb 20
Week 8
Feb 21 to Feb 27
Week 9
Feb 28 to Mar 5
Week 10
Mar 6 to Mar 12
Week 11
Mar 13 to Mar 19
Week 12
Mar 20 to Mar 26
Week 13
Mar 27 to Apr 2
Week 14
Apr 3 to Apr 9
Week 15
Apr 10 to Apr 16
Week 16
Apr 17 to Apr 23
Week 17
Apr 24 to Apr 30
Week 18
May 1 to May 7
Week 19
May 8 to May 14
Week 20
May 15 to May 21
Week 21
May 22 to May 28
Week 22
May 29 to Jun 4
Week 23
Jun 5 to Jun 11
Week 24
Jun 12 to Jun 18
Week 25
Jun 19 to Jun 25
Week 26
Jun 26 to Jul 2
Week 27
Jul 3 to Jul 9
Week 28
Jul 10 to Jul 16
Week 29
Jul 17 to Jul 23
Week 30
Jul 24 to Jul 30
Week 31
Jul 31 to Aug 6
Week 32
Aug 7 to Aug 13
Week 33
Aug 14 to Aug 20
Week 34
Aug 21 to Aug 27
Week 35
Aug 28 to Sep 3
Week 36
Sep 4 to Sep 10
Week 37
Sep 11 to Sep 17
Week 38
Sep 18 to Sep 24
Week 39
Sep 25 to Oct 1
Week 40
Oct 2 to Oct 8
Week 41
Oct 9 to Oct 15
Week 42
Oct 16 to Oct 22
Week 43
Oct 23 to Oct 29
Week 44
Oct 30 to Nov 5
Week 45
Nov 6 to Nov 12
Week 46
Nov 13 to Nov 19
Week 47
Nov 20 to Nov 26
Week 48
Nov 27 to Dec 3
Week 49
Dec 4 to Dec 10
Week 50
Dec 11 to Dec 17
Week 51
Dec 18 to Dec 24
Week 52
Dec 25 to Dec 31
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. 2028 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.