Week 12 of 2026 runs March 16 to March 22
ISO week 12 of 2026 begins on Monday, March 16, 2026 and ends on Sunday, March 22, 2026. It has already passed; the current week is 39. The week covers March only.
What dates are in week 12?
| Weekday | Date | Day of year | Notes |
|---|---|---|---|
| Monday | March 16, 2026 | 75 | |
| Tuesday | March 17, 2026 | 76 | St Patrick's Day |
| Wednesday | March 18, 2026 | 77 | |
| Thursday | March 19, 2026 | 78 | |
| Friday | March 20, 2026 | 79 | March equinox |
| Saturday | March 21, 2026 | 80 | |
| Sunday | March 22, 2026 | 81 |
Week 12 of 2026 contains St Patrick's Day on March 17 and March equinox on March 20. The seven dates always run Monday through Sunday, which is the part of ISO 8601 that most often catches people out: a week that starts on Sunday is a different convention and gives a different number.
How ISO week 12 is worked out
ISO 8601 fixes week one as the week containing the first Thursday of January, which is the same as saying the week containing 4 January, or the week holding the majority of its days in the new year. Counting forward from there, week 12 is the 12th Monday-to-Sunday block of 2026, which lands on March 16. All seven dates sit inside 2026, so the ISO year and the calendar year agree for this week.
When is week 12 in other years?
| Year | Monday | Sunday | Weeks in year |
|---|---|---|---|
| 2026 | March 16 | March 22 | 53 |
| 2027 | March 22 | March 28 | 52 |
| 2028 | March 20 | March 26 | 52 |
| 2029 | March 19 | March 25 | 52 |
| 2030 | March 18 | March 24 | 52 |
Week 12 shifts by a day or two each year because a year is 52 weeks plus one or two days, so the Monday that opens it moves from March 16 in 2026 to March 22 in 2027.
How far away is week 12?
Today is Wednesday, September 23, 2026, which sits in ISO week 39 of 2026. Week 12 of 2026 closed 185 days ago. The same week number in the following year is listed in the table above.
Questions
- What dates are in week 12 of 2026?
- Monday March 16, 2026 through Sunday March 22, 2026.
- What week is it now?
- ISO week 39 of 2026. Today is Wednesday, September 23, 2026.
- How many weeks does 2026 have?
- 53. The 2026 week count page explains the rule.
- Do ISO weeks start on Monday or Sunday?
- Monday. A Sunday-first week is a different convention and can give a different week number for the same date.
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