ISO Week · 2021 · Q4
Week 51
2021 · –
December · 5 working days · 98% through 2021
Week 51 of 2021 runs December 20, 2021 to December 26, 2021.
Week 51 starts on Monday, December 20, 2021 and ends on Sunday, December 26, 2021. It's the 354th day of the year, sits in Q4, and falls in December. By the end of this week, 360 of 365 days are gone, putting 2021 at 98.6%.
This week includes Christmas Day, Boxing Day, so it has 5 working days instead of the usual 5. Need a different week? Browse the full 2021 week calendar, or jump to this week's number.
Week 51 at a glance
The 7 days of week 51
Every date in week 51 of 2021, Monday through Sunday, with day-of-year numbers and events.
| Day | Date | Day no. | Type | Events |
|---|---|---|---|---|
| Monday | Day 354 | Weekday | ||
| Tuesday | Day 355 | Weekday | Winter Solstice | |
| Wednesday | Day 356 | Weekday | ||
| Thursday | Day 357 | Weekday | ||
| Friday | Day 358 | Weekday | ||
| Saturday | Day 359 | Weekend | Christmas Day | |
| Sunday | Day 360 | Weekend | Boxing Day |
What week 51 of 2021 means
ISO 8601 numbers weeks so every week starts on Monday and ends on Sunday. Week 1 is the one holding the year's first Thursday, which is why early January can land in week 52 or 53 of the previous year. Week 51 is one piece of that system.
In 2021, week 51 covers Dec 20 – Dec 26, 2021. That's December, deep in Q4. The same week number shifts by a day or two each year, so week 51 in 2022 won't share these exact dates. The table below shows how it moves.
Want to check a specific date instead of a week number? The week calculator converts any date to its ISO week. Curious how many weeks a year holds? The weeks in a year guide explains 52 versus 53. And the ISO week number page covers the standard end to end.
Holidays in week 51 of 2021
🇬🇧 United Kingdom
Boxing Day
Bank🇦🇺 Australia
Boxing Day
NationalWeek 51 across years
The same ISO week number lands on different dates each year. Here's how week 51 shifts.
| Year | From (Mon) | To (Sun) | Notable | |
|---|---|---|---|---|
| 2024 | view → |
Week 51 of 2021: questions and answers
What days are in week 51 of 2021?
Week 51 of 2021 runs from December 20, 2021 (Monday) through December 26, 2021 (Sunday). It spans December.
What month is week 51 in 2021?
Week 51 of 2021 falls entirely in December 2021.
How many working days are in week 51 of 2021?
Week 51 of 2021 has 5 working days.
What week is Christmas Day in 2021?
Christmas Day falls in ISO week 51 of 2021 (Dec 20 – Dec 26, 2021).
What quarter is week 51 of 2021 in?
Week 51 of 2021 is in Q4 (2021). The week starts on day 354 of 365.
What is ISO week 51?
ISO week 51 is defined by the ISO 8601 international standard. It begins on Monday, December 20, 2021, and ends on Sunday, December 26, 2021. It is week 98% through the ISO year 2021.