Week numbers 643

643 has 52 ISO weeks. Week 1: Jan 2 – 8 · Week 52: Dec 25 – 31

643 at a glance

Weeks in 64352
Week 1January 2, 643 – January 8, 643
Week 52December 25, 643 – December 31, 643
Days in 643365
Leap yearNo

All Weeks in 643

Week From To Month
Week 1 in 643 January 2, 643 January 8, 643 January
Week 2 in 643 January 9, 643 January 15, 643 January
Week 3 in 643 January 16, 643 January 22, 643 January
Week 4 in 643 January 23, 643 January 29, 643 January
Week 5 in 643 January 30, 643 February 5, 643 January / February
Week 6 in 643 February 6, 643 February 12, 643 February
Week 7 in 643 February 13, 643 February 19, 643 February
Week 8 in 643 February 20, 643 February 26, 643 February
Week 9 in 643 February 27, 643 March 5, 643 February / March
Week 10 in 643 March 6, 643 March 12, 643 March
Week 11 in 643 March 13, 643 March 19, 643 March
Week 12 in 643 March 20, 643 March 26, 643 March
Week 13 in 643 March 27, 643 April 2, 643 March / April
Week 14 in 643 April 3, 643 April 9, 643 April
Week 15 in 643 April 10, 643 April 16, 643 April
Week 16 in 643 April 17, 643 April 23, 643 April
Week 17 in 643 April 24, 643 April 30, 643 April
Week 18 in 643 May 1, 643 May 7, 643 May
Week 19 in 643 May 8, 643 May 14, 643 May
Week 20 in 643 May 15, 643 May 21, 643 May
Week 21 in 643 May 22, 643 May 28, 643 May
Week 22 in 643 May 29, 643 June 4, 643 May / June
Week 23 in 643 June 5, 643 June 11, 643 June
Week 24 in 643 June 12, 643 June 18, 643 June
Week 25 in 643 June 19, 643 June 25, 643 June
Week 26 in 643 June 26, 643 July 2, 643 June / July
Week 27 in 643 July 3, 643 July 9, 643 July
Week 28 in 643 July 10, 643 July 16, 643 July
Week 29 in 643 July 17, 643 July 23, 643 July
Week 30 in 643 July 24, 643 July 30, 643 July
Week 31 in 643 July 31, 643 August 6, 643 July / August
Week 32 in 643 August 7, 643 August 13, 643 August
Week 33 in 643 August 14, 643 August 20, 643 August
Week 34 in 643 August 21, 643 August 27, 643 August
Week 35 in 643 August 28, 643 September 3, 643 August / September
Week 36 in 643 September 4, 643 September 10, 643 September
Week 37 in 643 September 11, 643 September 17, 643 September
Week 38 in 643 September 18, 643 September 24, 643 September
Week 39 in 643 September 25, 643 October 1, 643 September / October
Week 40 in 643 October 2, 643 October 8, 643 October
Week 41 in 643 October 9, 643 October 15, 643 October
Week 42 in 643 October 16, 643 October 22, 643 October
Week 43 in 643 October 23, 643 October 29, 643 October
Week 44 in 643 October 30, 643 November 5, 643 October / November
Week 45 in 643 November 6, 643 November 12, 643 November
Week 46 in 643 November 13, 643 November 19, 643 November
Week 47 in 643 November 20, 643 November 26, 643 November
Week 48 in 643 November 27, 643 December 3, 643 November / December
Week 49 in 643 December 4, 643 December 10, 643 December
Week 50 in 643 December 11, 643 December 17, 643 December
Week 51 in 643 December 18, 643 December 24, 643 December
Week 52 in 643 December 25, 643 December 31, 643 December

Calendars 643

January 643
MoTuWeThFrSaSu
Week 521
Week 12345678
Week 29101112131415
Week 316171819202122
Week 423242526272829
Week 53031
February 643
MoTuWeThFrSaSu
Week 512345
Week 66789101112
Week 713141516171819
Week 820212223242526
Week 92728
March 643
MoTuWeThFrSaSu
Week 912345
Week 106789101112
Week 1113141516171819
Week 1220212223242526
Week 132728293031
April 643
MoTuWeThFrSaSu
Week 1312
Week 143456789
Week 1510111213141516
Week 1617181920212223
Week 1724252627282930
May 643
MoTuWeThFrSaSu
Week 181234567
Week 19891011121314
Week 2015161718192021
Week 2122232425262728
Week 22293031
June 643
MoTuWeThFrSaSu
Week 221234
Week 23567891011
Week 2412131415161718
Week 2519202122232425
Week 262627282930
July 643
MoTuWeThFrSaSu
Week 2612
Week 273456789
Week 2810111213141516
Week 2917181920212223
Week 3024252627282930
Week 3131
August 643
MoTuWeThFrSaSu
Week 31123456
Week 3278910111213
Week 3314151617181920
Week 3421222324252627
Week 3528293031
September 643
MoTuWeThFrSaSu
Week 35123
Week 3645678910
Week 3711121314151617
Week 3818192021222324
Week 39252627282930
October 643
MoTuWeThFrSaSu
Week 391
Week 402345678
Week 419101112131415
Week 4216171819202122
Week 4323242526272829
Week 443031
November 643
MoTuWeThFrSaSu
Week 4412345
Week 456789101112
Week 4613141516171819
Week 4720212223242526
Week 4827282930
December 643
MoTuWeThFrSaSu
Week 1123
Week 4945678910
Week 5011121314151617
Week 5118192021222324
Week 5225262728293031

Download Calendar in printable A4 PDF

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 643 starts on January 2, 643 and ends on January 8, 643 (ISO 8601, Monday to Sunday). 643 has 52 ISO weeks.

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 643 have?

643 has 52 ISO weeks.

When does week 1 of 643 start?

Week 1 of 643 starts on January 2, 643 and ends on January 8, 643 (ISO 8601, Monday to Sunday).

When does the last week of 643 end?

Week 52 of 643 starts on December 25, 643 and ends on December 31, 643 (ISO 8601, Monday to Sunday).

Which years have 53 weeks?

The next years with 53 ISO weeks are 646, 652, 657, 663, 668.

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.