2027 Week Numbers
2027 has 52 ISO weeks. Week 1 runs from Monday, January 4, to Sunday, January 10, 2027, while January 1–3 belong to week 53 of 2026. Every week's dates are listed below, and any calendar on this site can print a week-number column.
- 52 ISO weeks
- Week 1: Jan 4–10
- Jan 1–3: 2026-W53
All 2027 ISO week numbers
ISO weeks run from Monday to Sunday. January 1–3, 2027 belong to the last week of 2026, and week 52 ends on Sunday, January 2, 2028.
| Week | Dates (Monday–Sunday) |
|---|---|
| 2026-W53 | Dec 28, 2026 – Jan 3, 2027 |
| W01 | Jan 4 – Jan 10, 2027 |
| W02 | Jan 11 – Jan 17, 2027 |
| W03 | Jan 18 – Jan 24, 2027 |
| W04 | Jan 25 – Jan 31, 2027 |
| W05 | Feb 1 – Feb 7, 2027 |
| W06 | Feb 8 – Feb 14, 2027 |
| W07 | Feb 15 – Feb 21, 2027 |
| W08 | Feb 22 – Feb 28, 2027 |
| W09 | Mar 1 – Mar 7, 2027 |
| W10 | Mar 8 – Mar 14, 2027 |
| W11 | Mar 15 – Mar 21, 2027 |
| W12 | Mar 22 – Mar 28, 2027 |
| W13 | Mar 29 – Apr 4, 2027 |
| W14 | Apr 5 – Apr 11, 2027 |
| W15 | Apr 12 – Apr 18, 2027 |
| W16 | Apr 19 – Apr 25, 2027 |
| W17 | Apr 26 – May 2, 2027 |
| W18 | May 3 – May 9, 2027 |
| W19 | May 10 – May 16, 2027 |
| W20 | May 17 – May 23, 2027 |
| W21 | May 24 – May 30, 2027 |
| W22 | May 31 – Jun 6, 2027 |
| W23 | Jun 7 – Jun 13, 2027 |
| W24 | Jun 14 – Jun 20, 2027 |
| W25 | Jun 21 – Jun 27, 2027 |
| W26 | Jun 28 – Jul 4, 2027 |
| W27 | Jul 5 – Jul 11, 2027 |
| W28 | Jul 12 – Jul 18, 2027 |
| W29 | Jul 19 – Jul 25, 2027 |
| W30 | Jul 26 – Aug 1, 2027 |
| W31 | Aug 2 – Aug 8, 2027 |
| W32 | Aug 9 – Aug 15, 2027 |
| W33 | Aug 16 – Aug 22, 2027 |
| W34 | Aug 23 – Aug 29, 2027 |
| W35 | Aug 30 – Sep 5, 2027 |
| W36 | Sep 6 – Sep 12, 2027 |
| W37 | Sep 13 – Sep 19, 2027 |
| W38 | Sep 20 – Sep 26, 2027 |
| W39 | Sep 27 – Oct 3, 2027 |
| W40 | Oct 4 – Oct 10, 2027 |
| W41 | Oct 11 – Oct 17, 2027 |
| W42 | Oct 18 – Oct 24, 2027 |
| W43 | Oct 25 – Oct 31, 2027 |
| W44 | Nov 1 – Nov 7, 2027 |
| W45 | Nov 8 – Nov 14, 2027 |
| W46 | Nov 15 – Nov 21, 2027 |
| W47 | Nov 22 – Nov 28, 2027 |
| W48 | Nov 29 – Dec 5, 2027 |
| W49 | Dec 6 – Dec 12, 2027 |
| W50 | Dec 13 – Dec 19, 2027 |
| W51 | Dec 20 – Dec 26, 2027 |
| W52 | Dec 27, 2027 – Jan 2, 2028 |
How ISO week 1 is chosen
Under ISO 8601, week 1 is the week that contains the year's first Thursday — in 2027, the week of Monday, January 4. When a week crosses the new year, write the week year with the number, such as 2027-W52, to avoid confusion.
US week numbers
Many US calendars, and Excel's WEEKNUM function, count the week that contains January 1 as week 1. On this site, the US setting follows that rule with the week start you choose. With a Monday start, the US number is one higher than the ISO number all year; with a Sunday start, it is one or two higher, depending on the day. Payroll and retail calendars may use their own rules.
Print a 2027 calendar with week numbers
Set WEEK NOS to ISO or US in the calendar below, on any monthly calendar or on the 2027 yearly calendar to add a narrow week column. Leave it Off for a plain grid.
Frequently asked questions
How many weeks are in 2027?
2027 has 52 ISO weeks. Week 1 begins on Monday, January 4, 2027, and week 52 ends on Sunday, January 2, 2028.
What week number is January 1, 2027?
In ISO numbering, Friday, January 1, 2027 is in week 53 of 2026. Under the US rule used by Excel's WEEKNUM, it is week 1 of 2027.
How do I get week numbers in Excel?
Use =ISOWEEKNUM(A1) for ISO weeks. Use =WEEKNUM(A1) for US weeks that start on Sunday, or =WEEKNUM(A1,2) for weeks that start on Monday.
Can I print a calendar with week numbers?
Yes. Set WEEK NOS to ISO or US on any monthly or yearly calendar to add a narrow week column. It is Off by default.
| Sun | Mon | Tue | Wed | Thu | Fri | Sat |
|---|---|---|---|---|---|---|