Week 4, 2027
January 25–31, 2027
Monday January 25 – Sunday January 312027-W04Days 25–31
The seven days
| Date | ISO week date | Day of year | US week | Islamic date (computed) | Holidays and other dates |
|---|---|---|---|---|---|
| Mon, Jan 25 | 2027-W04-1 | 025 | 5 | 17 Sha'ban 1448 AH | |
| Tue, Jan 26 | 2027-W04-2 | 026 | 5 | 18 Sha'ban 1448 AH | Australia Day (4 sets) |
| Wed, Jan 27 | 2027-W04-3 | 027 | 5 | 19 Sha'ban 1448 AH | |
| Thu, Jan 28 | 2027-W04-4 | 028 | 5 | 20 Sha'ban 1448 AH | |
| Fri, Jan 29 | 2027-W04-5 | 029 | 5 | 21 Sha'ban 1448 AH | |
| Sat, Jan 30 | 2027-W04-6 | 030 | 5 | 22 Sha'ban 1448 AH | |
| Sun, Jan 31 | 2027-W04-7 | 031 | 6 | 23 Sha'ban 1448 AH |
About week 4
In US numbering, where weeks start on Sunday and the week of January 1 is week 1, Monday to Saturday are US week 5 and Sunday US week 6.
Holidays this week: Australia Day on Tue, Jan 26 in 4 of the countries and regions we cover. All weeks of 2027 lists the neighbouring weeks.
Week 4 in other years
| Year | Week 4 runs |
|---|---|
| 2025 | Mon, Jan 20 – Sun, Jan 26 |
| 2026 | Mon, Jan 19 – Sun, Jan 25 |
| 2027 | Mon, Jan 25 – Sun, Jan 31 |
| 2028 | Mon, Jan 24 – Sun, Jan 30 |
| 2029 | Mon, Jan 22 – Sun, Jan 28 |
| 2030 | Mon, Jan 21 – Sun, Jan 27 |
In 2028, week 4 runs Mon, Jan 24 – Sun, Jan 30: 364 days later, 1 day earlier in the calendar. Over the 400-year cycle, the Monday of week 4 falls between January 19 and January 25.
By the end of week 4, 31 days of 2027 have passed (8.5% of the year), and 48 ISO weeks of 2027 remain. The week falls in Q1.
Writing week 4
ISO 8601 writes this week as 2027-W04 (basic format 2027W04), from 2027-W04-1 on Monday to -7 on Sunday. The week number page shows the spreadsheet and Python formulas that give these numbers.