Week numbers 640

640 has 53 ISO weeks, because it is a leap year that starts on a Wednesday. Week 1: Dec 30, 639 – Jan 5, 640 · Week 53: Dec 28, 640 – Jan 3, 641

640 at a glance

Weeks in 64053
Week 1December 30, 639 – January 5, 640
Week 53December 28, 640 – January 3, 641
Days in 640366
Leap yearYes

All Weeks in 640

Week From To Month
Week 1 in 640 December 30, 639 January 5, 640 December / January
Week 2 in 640 January 6, 640 January 12, 640 January
Week 3 in 640 January 13, 640 January 19, 640 January
Week 4 in 640 January 20, 640 January 26, 640 January
Week 5 in 640 January 27, 640 February 2, 640 January / February
Week 6 in 640 February 3, 640 February 9, 640 February
Week 7 in 640 February 10, 640 February 16, 640 February
Week 8 in 640 February 17, 640 February 23, 640 February
Week 9 in 640 February 24, 640 March 1, 640 February / March
Week 10 in 640 March 2, 640 March 8, 640 March
Week 11 in 640 March 9, 640 March 15, 640 March
Week 12 in 640 March 16, 640 March 22, 640 March
Week 13 in 640 March 23, 640 March 29, 640 March
Week 14 in 640 March 30, 640 April 5, 640 March / April
Week 15 in 640 April 6, 640 April 12, 640 April
Week 16 in 640 April 13, 640 April 19, 640 April
Week 17 in 640 April 20, 640 April 26, 640 April
Week 18 in 640 April 27, 640 May 3, 640 April / May
Week 19 in 640 May 4, 640 May 10, 640 May
Week 20 in 640 May 11, 640 May 17, 640 May
Week 21 in 640 May 18, 640 May 24, 640 May
Week 22 in 640 May 25, 640 May 31, 640 May
Week 23 in 640 June 1, 640 June 7, 640 June
Week 24 in 640 June 8, 640 June 14, 640 June
Week 25 in 640 June 15, 640 June 21, 640 June
Week 26 in 640 June 22, 640 June 28, 640 June
Week 27 in 640 June 29, 640 July 5, 640 June / July
Week 28 in 640 July 6, 640 July 12, 640 July
Week 29 in 640 July 13, 640 July 19, 640 July
Week 30 in 640 July 20, 640 July 26, 640 July
Week 31 in 640 July 27, 640 August 2, 640 July / August
Week 32 in 640 August 3, 640 August 9, 640 August
Week 33 in 640 August 10, 640 August 16, 640 August
Week 34 in 640 August 17, 640 August 23, 640 August
Week 35 in 640 August 24, 640 August 30, 640 August
Week 36 in 640 August 31, 640 September 6, 640 August / September
Week 37 in 640 September 7, 640 September 13, 640 September
Week 38 in 640 September 14, 640 September 20, 640 September
Week 39 in 640 September 21, 640 September 27, 640 September
Week 40 in 640 September 28, 640 October 4, 640 September / October
Week 41 in 640 October 5, 640 October 11, 640 October
Week 42 in 640 October 12, 640 October 18, 640 October
Week 43 in 640 October 19, 640 October 25, 640 October
Week 44 in 640 October 26, 640 November 1, 640 October / November
Week 45 in 640 November 2, 640 November 8, 640 November
Week 46 in 640 November 9, 640 November 15, 640 November
Week 47 in 640 November 16, 640 November 22, 640 November
Week 48 in 640 November 23, 640 November 29, 640 November
Week 49 in 640 November 30, 640 December 6, 640 November / December
Week 50 in 640 December 7, 640 December 13, 640 December
Week 51 in 640 December 14, 640 December 20, 640 December
Week 52 in 640 December 21, 640 December 27, 640 December
Week 53 in 640 December 28, 640 January 3, 641 December / January

Calendars 640

January 640
MoTuWeThFrSaSu
Week 112345
Week 26789101112
Week 313141516171819
Week 420212223242526
Week 52728293031
February 640
MoTuWeThFrSaSu
Week 512
Week 63456789
Week 710111213141516
Week 817181920212223
Week 9242526272829
March 640
MoTuWeThFrSaSu
Week 91
Week 102345678
Week 119101112131415
Week 1216171819202122
Week 1323242526272829
Week 143031
April 640
MoTuWeThFrSaSu
Week 1412345
Week 156789101112
Week 1613141516171819
Week 1720212223242526
Week 1827282930
May 640
MoTuWeThFrSaSu
Week 18123
Week 1945678910
Week 2011121314151617
Week 2118192021222324
Week 2225262728293031
June 640
MoTuWeThFrSaSu
Week 231234567
Week 24891011121314
Week 2515161718192021
Week 2622232425262728
Week 272930
July 640
MoTuWeThFrSaSu
Week 2712345
Week 286789101112
Week 2913141516171819
Week 3020212223242526
Week 312728293031
August 640
MoTuWeThFrSaSu
Week 3112
Week 323456789
Week 3310111213141516
Week 3417181920212223
Week 3524252627282930
Week 3631
September 640
MoTuWeThFrSaSu
Week 36123456
Week 3778910111213
Week 3814151617181920
Week 3921222324252627
Week 40282930
October 640
MoTuWeThFrSaSu
Week 401234
Week 41567891011
Week 4212131415161718
Week 4319202122232425
Week 44262728293031
November 640
MoTuWeThFrSaSu
Week 441
Week 452345678
Week 469101112131415
Week 4716171819202122
Week 4823242526272829
Week 4930
December 640
MoTuWeThFrSaSu
Week 2123456
Week 5078910111213
Week 5114151617181920
Week 5221222324252627
Week 5328293031

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Find the week number of a date

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 640 starts on December 30, 639 and ends on January 5, 640 (ISO 8601, Monday to Sunday). 640 has 53 ISO weeks, because it is a leap year that starts on a Wednesday.

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.

Frequently Asked Questions (FAQ)

How many weeks does 640 have?

640 has 53 ISO weeks, because it is a leap year that starts on a Wednesday.

When does week 1 of 640 start?

Week 1 of 640 starts on December 30, 639 and ends on January 5, 640 (ISO 8601, Monday to Sunday).

When does the last week of 640 end?

Week 53 of 640 starts on December 28, 640 and ends on January 3, 641 (ISO 8601, Monday to Sunday).

Which years have 53 weeks?

The next years with 53 ISO weeks are 640, 646, 652, 657, 663.

Why do the US and Europe show different week numbers?

Europe follows ISO 8601: weeks start on Monday and week 1 is the week with the first Thursday of the year. In the US, weeks usually start on Sunday and week 1 is the week that contains 1 January, so the two numbers can differ by one.