Week Numbers
ISO week numbers for 2027
See the week number for every date in 2027. ISO 8601 standard — weeks start on Monday, and week 1 contains the first Thursday of January.
| Week | Start Date | End Date | Month |
|---|---|---|---|
| 1 | Jan 4, 2027 | Jan 10, 2027 | January |
| 2 | Jan 11, 2027 | Jan 17, 2027 | January |
| 3 | Jan 18, 2027 | Jan 24, 2027 | January |
| 4 | Jan 25, 2027 | Jan 31, 2027 | January |
| 5 | Feb 1, 2027 | Feb 7, 2027 | February |
| 6 | Feb 8, 2027 | Feb 14, 2027 | February |
| 7 | Feb 15, 2027 | Feb 21, 2027 | February |
| 8 | Feb 22, 2027 | Feb 28, 2027 | February |
| 9 | Mar 1, 2027 | Mar 7, 2027 | March |
| 10 | Mar 8, 2027 | Mar 14, 2027 | March |
| 11 | Mar 15, 2027 | Mar 21, 2027 | March |
| 12 | Mar 22, 2027 | Mar 28, 2027 | March |
| 13 | Mar 29, 2027 | Apr 4, 2027 | April |
| 14 | Apr 5, 2027 | Apr 11, 2027 | April |
| 15 | Apr 12, 2027 | Apr 18, 2027 | April |
| 16 | Apr 19, 2027 | Apr 25, 2027 | April |
| 17 | Apr 26, 2027 | May 2, 2027 | May |
| 18 | May 3, 2027 | May 9, 2027 | May |
| 19 | May 10, 2027 | May 16, 2027 | May |
| 20 | May 17, 2027 | May 23, 2027 | May |
| 21 | May 24, 2027 | May 30, 2027 | May |
| 22 | May 31, 2027 | Jun 6, 2027 | June |
| 23 | Jun 7, 2027 | Jun 13, 2027 | June |
| 24 | Jun 14, 2027 | Jun 20, 2027 | June |
| 25 | Jun 21, 2027 | Jun 27, 2027 | June |
| 26 | Jun 28, 2027 | Jul 4, 2027 | July |
| 27 | Jul 5, 2027 | Jul 11, 2027 | July |
| 28 | Jul 12, 2027 | Jul 18, 2027 | July |
| 29 | Jul 19, 2027 | Jul 25, 2027 | July |
| 30 | Jul 26, 2027 | Aug 1, 2027 | August |
| 31 | Aug 2, 2027 | Aug 8, 2027 | August |
| 32 | Aug 9, 2027 | Aug 15, 2027 | August |
| 33 | Aug 16, 2027 | Aug 22, 2027 | August |
| 34 | Aug 23, 2027 | Aug 29, 2027 | August |
| 35 | Aug 30, 2027 | Sep 5, 2027 | September |
| 36 | Sep 6, 2027 | Sep 12, 2027 | September |
| 37 | Sep 13, 2027 | Sep 19, 2027 | September |
| 38 | Sep 20, 2027 | Sep 26, 2027 | September |
| 39 | Sep 27, 2027 | Oct 3, 2027 | October |
| 40 | Oct 4, 2027 | Oct 10, 2027 | October |
| 41 | Oct 11, 2027 | Oct 17, 2027 | October |
| 42 | Oct 18, 2027 | Oct 24, 2027 | October |
| 43 | Oct 25, 2027 | Oct 31, 2027 | October |
| 44 | Nov 1, 2027 | Nov 7, 2027 | November |
| 45 | Nov 8, 2027 | Nov 14, 2027 | November |
| 46 | Nov 15, 2027 | Nov 21, 2027 | November |
| 47 | Nov 22, 2027 | Nov 28, 2027 | November |
| 48 | Nov 29, 2027 | Dec 5, 2027 | December |
| 49 | Dec 6, 2027 | Dec 12, 2027 | December |
| 50 | Dec 13, 2027 | Dec 19, 2027 | December |
| 51 | Dec 20, 2027 | Dec 26, 2027 | December |
| 52 | Dec 27, 2027 | Jan 2, 2028 | January |
ISO 8601 defines week 1 as the week containing the first Thursday of January. Weeks start on Monday. A year has 52 weeks most years, or 53 weeks when January 1 falls on a Thursday (or Wednesday in a leap year).
Frequently asked questions
- What is ISO 8601 week numbering?
- ISO 8601 is an international standard for date and time formatting. Under this standard, weeks start on Monday, and week 1 is the week containing the first Thursday of January. This ensures each week belongs to exactly one year.
- Why does 2027 have 52 weeks?
- Most years have 52 ISO weeks. A year has 53 weeks when January 1 falls on a Thursday, or on a Wednesday in a leap year. This happens because the extra days push a partial week into a 53rd slot.
- How do I find the week number for a specific date?
- Use the Week Number Calculator to enter any date and get its ISO week number, ISO year and date range instantly.