Week numbers 2027
When does week 1 of 2027 start? On January 4, 2027 (ISO 8601).
52ISO weeks in 2027
Mon, Jan 4week 1 starts
Sun, Jan 2week 52 ends
2027 has 52 ISO weeks. These are ISO 8601 week numbers, used in Europe, most of the world and by Excel's ISOWEEKNUM: weeks start on Monday and week 1 is the week with the year's first Thursday. In the US, many calendars start weeks on Sunday and count the week containing January 1 as week 1, so the US number can be one higher.
| Week | Monday | Sunday | US federal holidays |
|---|---|---|---|
| 1 | Mon, Jan 4 | Sun, Jan 10 | |
| 2 | Mon, Jan 11 | Sun, Jan 17 | |
| 3 | Mon, Jan 18 | Sun, Jan 24 | Martin Luther King Jr. Day |
| 4 | Mon, Jan 25 | Sun, Jan 31 | |
| 5 | Mon, Feb 1 | Sun, Feb 7 | |
| 6 | Mon, Feb 8 | Sun, Feb 14 | |
| 7 | Mon, Feb 15 | Sun, Feb 21 | Washington's Birthday |
| 8 | Mon, Feb 22 | Sun, Feb 28 | |
| 9 | Mon, Mar 1 | Sun, Mar 7 | |
| 10 | Mon, Mar 8 | Sun, Mar 14 | |
| 11 | Mon, Mar 15 | Sun, Mar 21 | |
| 12 | Mon, Mar 22 | Sun, Mar 28 | |
| 13 | Mon, Mar 29 | Sun, Apr 4 | |
| 14 | Mon, Apr 5 | Sun, Apr 11 | |
| 15 | Mon, Apr 12 | Sun, Apr 18 | |
| 16 | Mon, Apr 19 | Sun, Apr 25 | |
| 17 | Mon, Apr 26 | Sun, May 2 | |
| 18 | Mon, May 3 | Sun, May 9 | |
| 19 | Mon, May 10 | Sun, May 16 | |
| 20 | Mon, May 17 | Sun, May 23 | |
| 21 | Mon, May 24 | Sun, May 30 | |
| 22 | Mon, May 31 | Sun, Jun 6 | Memorial Day |
| 23 | Mon, Jun 7 | Sun, Jun 13 | |
| 24 | Mon, Jun 14 | Sun, Jun 20 | Juneteenth National Independence Day (observed), Juneteenth National Independence Day |
| 25 | Mon, Jun 21 | Sun, Jun 27 | |
| 26 | Mon, Jun 28 | Sun, Jul 4 | Independence Day |
| 27 | Mon, Jul 5 | Sun, Jul 11 | Independence Day (observed) |
| 28 | Mon, Jul 12 | Sun, Jul 18 | |
| 29 | Mon, Jul 19 | Sun, Jul 25 | |
| 30 | Mon, Jul 26 | Sun, Aug 1 | |
| 31 | Mon, Aug 2 | Sun, Aug 8 | |
| 32 | Mon, Aug 9 | Sun, Aug 15 | |
| 33 | Mon, Aug 16 | Sun, Aug 22 | |
| 34 | Mon, Aug 23 | Sun, Aug 29 | |
| 35 | Mon, Aug 30 | Sun, Sep 5 | |
| 36 | Mon, Sep 6 | Sun, Sep 12 | Labor Day |
| 37 | Mon, Sep 13 | Sun, Sep 19 | |
| 38 | Mon, Sep 20 | Sun, Sep 26 | |
| 39 | Mon, Sep 27 | Sun, Oct 3 | |
| 40 | Mon, Oct 4 | Sun, Oct 10 | |
| 41 | Mon, Oct 11 | Sun, Oct 17 | Columbus Day |
| 42 | Mon, Oct 18 | Sun, Oct 24 | |
| 43 | Mon, Oct 25 | Sun, Oct 31 | |
| 44 | Mon, Nov 1 | Sun, Nov 7 | |
| 45 | Mon, Nov 8 | Sun, Nov 14 | Veterans Day |
| 46 | Mon, Nov 15 | Sun, Nov 21 | |
| 47 | Mon, Nov 22 | Sun, Nov 28 | Thanksgiving Day |
| 48 | Mon, Nov 29 | Sun, Dec 5 | |
| 49 | Mon, Dec 6 | Sun, Dec 12 | |
| 50 | Mon, Dec 13 | Sun, Dec 19 | |
| 51 | Mon, Dec 20 | Sun, Dec 26 | Christmas Day (observed), Christmas Day |
| 52 | Mon, Dec 27 | Sun, Jan 2 | New Year's Day (observed), New Year's Day |
Week number in Excel and Google Sheets
- ISO week (Monday start)=ISOWEEKNUM(A1)
- US week (Sunday start)=WEEKNUM(A1)
- Current ISO week=ISOWEEKNUM(TODAY())
Questions
How many weeks are in 2027?
2027 has 52 ISO weeks.
When does week 1 of 2027 start?
On January 4, 2027 (ISO 8601).
- Current week number
- Week numbers 2026
- Week numbers 2028
- 2027 calendar
Federal holidays follow the US Office of Personnel Management (OPM) list; dates are calculated, not estimated.