Week 51, 2026
December 14–20, 2026
Monday December 14 – Sunday December 202026-W51Days 348–354
The seven days
| Date | ISO week date | Day of year | US week | Islamic date (computed) | Holidays and other dates |
|---|---|---|---|---|---|
| Mon, Dec 14 | 2026-W51-1 | 348 | 51 | 5 Rajab 1448 AH | |
| Tue, Dec 15 | 2026-W51-2 | 349 | 51 | 6 Rajab 1448 AH | |
| Wed, Dec 16 | 2026-W51-3 | 350 | 51 | 7 Rajab 1448 AH | Day of Reconciliation (South Africa) |
| Thu, Dec 17 | 2026-W51-4 | 351 | 51 | 8 Rajab 1448 AH | |
| Fri, Dec 18 | 2026-W51-5 | 352 | 51 | 9 Rajab 1448 AH | |
| Sat, Dec 19 | 2026-W51-6 | 353 | 51 | 10 Rajab 1448 AH | |
| Sun, Dec 20 | 2026-W51-7 | 354 | 52 | 11 Rajab 1448 AH |
About week 51
In US numbering, where weeks start on Sunday and the week of January 1 is week 1, Monday to Saturday are US week 51 and Sunday US week 52.
Holidays this week: Day of Reconciliation on Wed, Dec 16 in South Africa. All weeks of 2026 lists the neighbouring weeks.
Week 51 in other years
| Year | Week 51 runs |
|---|---|
| 2024 | Mon, Dec 16 – Sun, Dec 22 |
| 2025 | Mon, Dec 15 – Sun, Dec 21 |
| 2026 | Mon, Dec 14 – Sun, Dec 20 |
| 2027 | Mon, Dec 20 – Sun, Dec 26 |
| 2028 | Mon, Dec 18 – Sun, Dec 24 |
| 2029 | Mon, Dec 17 – Sun, Dec 23 |
In 2027, week 51 runs Mon, Dec 20 – Sun, Dec 26: 2026 has 53 weeks, so the same number comes 371 days later, 6 days later in the calendar. Over the 400-year cycle, the Monday of week 51 falls between December 13 and December 20.
By the end of week 51, 354 days of 2026 have passed (97.0% of the year), and 2 ISO weeks of 2026 remain. The week falls in Q4.
Writing week 51
ISO 8601 writes this week as 2026-W51 (basic format 2026W51), from 2026-W51-1 on Monday to -7 on Sunday. The week number page shows the spreadsheet and Python formulas that give these numbers.