Week numbers 2027
52 ISO weeksWeek 1: January 4 – January 10Week 52 ends January 2, 2028
All weeks of 2027
| Week | Monday | Sunday | Month | US week | US federal holiday |
|---|---|---|---|---|---|
| Week 1 | Mon, Jan 4 | Sun, Jan 10 | January | 2/3 | |
| Week 2 | Mon, Jan 11 | Sun, Jan 17 | January | 3/4 | |
| Week 3 | Mon, Jan 18 | Sun, Jan 24 | January | 4/5 | Birthday of Martin Luther King, Jr. |
| Week 4 | Mon, Jan 25 | Sun, Jan 31 | January | 5/6 | |
| Week 5 | Mon, Feb 1 | Sun, Feb 7 | February | 6/7 | |
| Week 6 | Mon, Feb 8 | Sun, Feb 14 | February | 7/8 | |
| Week 7 | Mon, Feb 15 | Sun, Feb 21 | February | 8/9 | Washington's Birthday |
| Week 8 | Mon, Feb 22 | Sun, Feb 28 | February | 9/10 | |
| Week 9 | Mon, Mar 1 | Sun, Mar 7 | March | 10/11 | |
| Week 10 | Mon, Mar 8 | Sun, Mar 14 | March | 11/12 | |
| Week 11 | Mon, Mar 15 | Sun, Mar 21 | March | 12/13 | |
| Week 12 | Mon, Mar 22 | Sun, Mar 28 | March | 13/14 | |
| Week 13 | Mon, Mar 29 | Sun, Apr 4 | Mar–Apr | 14/15 | |
| Week 14 | Mon, Apr 5 | Sun, Apr 11 | April | 15/16 | |
| Week 15 | Mon, Apr 12 | Sun, Apr 18 | April | 16/17 | |
| Week 16 | Mon, Apr 19 | Sun, Apr 25 | April | 17/18 | |
| Week 17 | Mon, Apr 26 | Sun, May 2 | Apr–May | 18/19 | |
| Week 18 | Mon, May 3 | Sun, May 9 | May | 19/20 | |
| Week 19 | Mon, May 10 | Sun, May 16 | May | 20/21 | |
| Week 20 | Mon, May 17 | Sun, May 23 | May | 21/22 | |
| Week 21 | Mon, May 24 | Sun, May 30 | May | 22/23 | |
| Week 22 | Mon, May 31 | Sun, Jun 6 | May–Jun | 23/24 | Memorial Day |
| Week 23 | Mon, Jun 7 | Sun, Jun 13 | June | 24/25 | |
| Week 24 | Mon, Jun 14 | Sun, Jun 20 | June | 25/26 | Juneteenth National Independence Day (observed) |
| Week 25 | Mon, Jun 21 | Sun, Jun 27 | June | 26/27 | |
| Week 26 | Mon, Jun 28 | Sun, Jul 4 | Jun–Jul | 27/28 | |
| Week 27 | Mon, Jul 5 | Sun, Jul 11 | July | 28/29 | Independence Day (observed) |
| Week 28 | Mon, Jul 12 | Sun, Jul 18 | July | 29/30 | |
| Week 29 | Mon, Jul 19 | Sun, Jul 25 | July | 30/31 | |
| Week 30 | Mon, Jul 26 | Sun, Aug 1 | Jul–Aug | 31/32 | |
| Week 31 | Mon, Aug 2 | Sun, Aug 8 | August | 32/33 | |
| Week 32 | Mon, Aug 9 | Sun, Aug 15 | August | 33/34 | |
| Week 33 | Mon, Aug 16 | Sun, Aug 22 | August | 34/35 | |
| Week 34 | Mon, Aug 23 | Sun, Aug 29 | August | 35/36 | |
| Week 35 | Mon, Aug 30 | Sun, Sep 5 | Aug–Sep | 36/37 | |
| Week 36 | Mon, Sep 6 | Sun, Sep 12 | September | 37/38 | Labor Day |
| Week 37 | Mon, Sep 13 | Sun, Sep 19 | September | 38/39 | |
| Week 38 | Mon, Sep 20 | Sun, Sep 26 | September | 39/40 | |
| Week 39 | Mon, Sep 27 | Sun, Oct 3 | Sep–Oct | 40/41 | |
| Week 40 | Mon, Oct 4 | Sun, Oct 10 | October | 41/42 | |
| Week 41 | Mon, Oct 11 | Sun, Oct 17 | October | 42/43 | Columbus Day |
| Week 42 | Mon, Oct 18 | Sun, Oct 24 | October | 43/44 | |
| Week 43 | Mon, Oct 25 | Sun, Oct 31 | October | 44/45 | |
| Week 44 | Mon, Nov 1 | Sun, Nov 7 | November | 45/46 | |
| Week 45 | Mon, Nov 8 | Sun, Nov 14 | November | 46/47 | Veterans Day |
| Week 46 | Mon, Nov 15 | Sun, Nov 21 | November | 47/48 | |
| Week 47 | Mon, Nov 22 | Sun, Nov 28 | November | 48/49 | Thanksgiving Day |
| Week 48 | Mon, Nov 29 | Sun, Dec 5 | Nov–Dec | 49/50 | |
| Week 49 | Mon, Dec 6 | Sun, Dec 12 | December | 50/51 | |
| Week 50 | Mon, Dec 13 | Sun, Dec 19 | December | 51/52 | |
| Week 51 | Mon, Dec 20 | Sun, Dec 26 | December | 52/53 | Christmas Day (observed) |
| Week 52 | Mon, Dec 27 | Sun, Jan 2 2028 | Dec–Jan | 53/1/2 | New Year's Day (observed) |
US week: the Sunday-start number for the same seven days; the ISO week’s Sunday always starts the next US week, and around New Year the US count restarts at 1 on January 1, so a week can carry three numbers (Monday to December 31, January 1 to Saturday, Sunday).
How the weeks of 2027 are numbered
January 1, 2027 is a Friday, so it still belongs to week 53 of 2026. Week 1 of 2027 begins on Monday, January 4. December 31 is in week 52, the last week of the ISO year. 2027 has the usual 52 ISO weeks.
The week number page shows the current week and explains the ISO 8601 rules; the 2027 calendar shows the weeks next to each month.
Which week is it in 2027?
The ISO week of each US federal holiday and of the main observances of 2027, computed from their rules (movable feasts such as Easter and Ramadan included):
- New Year's Day, Fri, Jan 1week 53 of 2026
- Birthday of Martin Luther King, Jr., Mon, Jan 18week 3
- Chinese New Year (Fire Goat), Sat, Feb 6week 5
- Ramadan begins, Mon, Feb 8week 6
- Ash Wednesday, Wed, Feb 10week 6
- Valentine’s Day, Sun, Feb 14week 6
- Washington's Birthday, Mon, Feb 15week 7
- Mothering Sunday (UK and Ireland), Sun, Mar 7week 9
- Eid al-Fitr, Tue, Mar 9week 10
- Palm Sunday, Sun, Mar 21week 11
- Nowruz 1406, Sun, Mar 21week 11
- Easter Sunday, Sun, Mar 28week 12
- Passover (first day), Thu, Apr 22week 16
- Mother’s Day (US, Canada), Sun, May 9week 18
- Eid al-Adha, Sun, May 16week 19
- Memorial Day, Mon, May 31week 22
- Islamic New Year 1449 AH, Sun, Jun 6week 22
- Juneteenth National Independence Day (observed), Fri, Jun 18week 24
- Father’s Day (US, UK, Canada), Sun, Jun 20week 24
- Independence Day (observed), Mon, Jul 5week 27
- Labor Day, Mon, Sep 6week 36
- Mid-Autumn Festival, Wed, Sep 15week 37
- Rosh Hashanah 5788, Sat, Oct 2week 39
- Columbus Day, Mon, Oct 11week 41
- Yom Kippur, Mon, Oct 11week 41
- Halloween, Sun, Oct 31week 43
- Veterans Day, Thu, Nov 11week 45
- Thanksgiving Day, Thu, Nov 25week 47
- Black Friday (US), Fri, Nov 26week 47
- Christmas Day (observed), Fri, Dec 24week 51
- Christmas Eve, Fri, Dec 24week 51
- Hanukkah (first day), Sat, Dec 25week 51
- New Year’s Eve, Fri, Dec 31week 52
Questions
How many weeks are in 2027?
2027 has 52 ISO weeks, from Monday, January 4 to Sunday, January 2, 2028.
When does week 1 of 2027 start?
On Monday, January 4. January 1, 2027 is a Friday, so it still belongs to week 53 of 2026. Week 1 of 2027 begins on Monday, January 4.
Is there a week 53 in 2027?
No. A year has a week 53 only when January 1 is a Thursday, or a Wednesday in a leap year. January 1, 2027 is a Friday.
Why do US week numbers differ in 2027?
US-style numbering starts weeks on Sunday and makes the week of January 1 week 1. Because January 1, 2027 is a Friday, the US system counts that short week as week 1 while ISO puts it in the previous year, so the US number is one higher from Monday to Saturday and two higher on Sundays. In the last days of December the US count starts again at 1.