Week 21 in 2009
Week 21 of 2009 begins on May 18, 2009 and ends on May 24, 2009. It covers days 138 to 144 of the year and falls in quarter 2.
Weeks since this week: 907
Week 21 of 2009 at a glance
| Starts (Monday) | May 18, 2009 |
|---|---|
| Ends (Sunday) | May 24, 2009 |
| US week (Sunday to Saturday) | 21 (May 17, 2009) |
| Month | May |
| Quarter | Q2 |
| Days of the year | 138–144 |
| Year completed at the end of this week | 39.5% |
| Weeks left in 2009 after this week | 32 |
| Weeks in 2009 | 53 |
| Even or odd week | Odd |
Calendar for May 2009
Download Calendar in printable A4 PDF
(US version) (EU/ISO Version)
All Weeks in 2009:
Past & Future Week Number 21:
US and ISO week numbers
In the US system, where weeks start on Sunday and week 1 is the week that contains 1 January, this is week 21 of 2009. It runs from May 17, 2009 to May 23, 2009.
Even and odd weeks
Week 21 is an odd week. Even and odd week numbers are used for alternating schedules such as shift rotas, school timetables, custody arrangements and waste collection.
Week 21 in other years
| From | To | |
|---|---|---|
| Week 21 in 2007 | May 21, 2007 | May 27, 2007 |
| Week 21 in 2008 | May 19, 2008 | May 25, 2008 |
| Week 21 in 2010 | May 24, 2010 | May 30, 2010 |
| Week 21 in 2011 | May 23, 2011 | May 29, 2011 |
How week numbers are counted
Most of the world numbers weeks according to the ISO 8601 standard. A week starts on Monday, and week 1 is the week that contains the first Thursday of the year, which is always the week that contains 4 January.
Week 1 of 2009 began on December 29, 2008. 2009 has 53 ISO weeks, because 1 January 2009 falls on a Thursday.
Because of this rule, the first days of January can belong to the last week of the previous year, and the last days of December can belong to week 1 of the next year.
In the United States, weeks usually start on Sunday and week 1 is the week that contains 1 January, so the US week number can differ from the ISO week number.
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Frequently Asked Questions (FAQ)
When does week 21 of 2009 start and end?
Week 21 of 2009 starts on May 18, 2009 and ends on May 24, 2009 (ISO 8601, Monday to Sunday).
Which month is week 21 of 2009 in?
Week 21 of 2009 is in May.
What dates are in week 21 of 2009?
May 18, 2009, May 19, 2009, May 20, 2009, May 21, 2009, May 22, 2009, May 23, 2009, and May 24, 2009
How many weeks does 2009 have?
2009 has 53 ISO weeks, because 1 January 2009 falls on a Thursday.
Is week 21 an even or odd week?
Week 21 is an odd week.
What is the US week number for this week?
In the US system, where weeks start on Sunday and week 1 is the week that contains 1 January, this is week 21 of 2009. It runs from May 17, 2009 to May 23, 2009.