All calendar weeks 2021 - CW 2021

Updated on by Michael Mühl

The calendar year 2021 begins on Friday, January 1, 2021 and ends on Friday, December 31, 2021.

Table of all European and Asian ISO calendar weeks for 2021

The following table shows all ISO calendar weeks 2021 from 1 to 53, with their start date beginning on Monday and their end date falling on Sunday.

European and Asian ISO calendar weeks 2021 - CW 2021
CWStart of the CWEnd of the CWISO-Name
1Monday, January 4, 2021Sunday, January 10, 20212021‑W01
2Monday, January 11, 2021Sunday, January 17, 20212021‑W02
3Monday, January 18, 2021Sunday, January 24, 20212021‑W03
4Monday, January 25, 2021Sunday, January 31, 20212021‑W04
5Monday, February 1, 2021Sunday, February 7, 20212021‑W05
6Monday, February 8, 2021Sunday, February 14, 20212021‑W06
7Monday, February 15, 2021Sunday, February 21, 20212021‑W07
8Monday, February 22, 2021Sunday, February 28, 20212021‑W08
9Monday, March 1, 2021Sunday, March 7, 20212021‑W09
10Monday, March 8, 2021Sunday, March 14, 20212021‑W10
11Monday, March 15, 2021Sunday, March 21, 20212021‑W11
12Monday, March 22, 2021Sunday, March 28, 20212021‑W12
13Monday, March 29, 2021Sunday, April 4, 20212021‑W13
14Monday, April 5, 2021Sunday, April 11, 20212021‑W14
15Monday, April 12, 2021Sunday, April 18, 20212021‑W15
16Monday, April 19, 2021Sunday, April 25, 20212021‑W16
17Monday, April 26, 2021Sunday, May 2, 20212021‑W17
18Monday, May 3, 2021Sunday, May 9, 20212021‑W18
19Monday, May 10, 2021Sunday, May 16, 20212021‑W19
20Monday, May 17, 2021Sunday, May 23, 20212021‑W20
21Monday, May 24, 2021Sunday, May 30, 20212021‑W21
22Monday, May 31, 2021Sunday, June 6, 20212021‑W22
23Monday, June 7, 2021Sunday, June 13, 20212021‑W23
24Monday, June 14, 2021Sunday, June 20, 20212021‑W24
25Monday, June 21, 2021Sunday, June 27, 20212021‑W25
26Monday, June 28, 2021Sunday, July 4, 20212021‑W26
27Monday, July 5, 2021Sunday, July 11, 20212021‑W27
28Monday, July 12, 2021Sunday, July 18, 20212021‑W28
29Monday, July 19, 2021Sunday, July 25, 20212021‑W29
30Monday, July 26, 2021Sunday, August 1, 20212021‑W30
31Monday, August 2, 2021Sunday, August 8, 20212021‑W31
32Monday, August 9, 2021Sunday, August 15, 20212021‑W32
33Monday, August 16, 2021Sunday, August 22, 20212021‑W33
34Monday, August 23, 2021Sunday, August 29, 20212021‑W34
35Monday, August 30, 2021Sunday, September 5, 20212021‑W35
36Monday, September 6, 2021Sunday, September 12, 20212021‑W36
37Monday, September 13, 2021Sunday, September 19, 20212021‑W37
38Monday, September 20, 2021Sunday, September 26, 20212021‑W38
39Monday, September 27, 2021Sunday, October 3, 20212021‑W39
40Monday, October 4, 2021Sunday, October 10, 20212021‑W40
41Monday, October 11, 2021Sunday, October 17, 20212021‑W41
42Monday, October 18, 2021Sunday, October 24, 20212021‑W42
43Monday, October 25, 2021Sunday, October 31, 20212021‑W43
44Monday, November 1, 2021Sunday, November 7, 20212021‑W44
45Monday, November 8, 2021Sunday, November 14, 20212021‑W45
46Monday, November 15, 2021Sunday, November 21, 20212021‑W46
47Monday, November 22, 2021Sunday, November 28, 20212021‑W47
48Monday, November 29, 2021Sunday, December 5, 20212021‑W48
49Monday, December 6, 2021Sunday, December 12, 20212021‑W49
50Monday, December 13, 2021Sunday, December 19, 20212021‑W50
51Monday, December 20, 2021Sunday, December 26, 20212021‑W51
52Monday, December 27, 2021Sunday, January 2, 20222021‑W52
532021 does not exist week 532021 has only 52 calendar weeks2021‑W53

The ISO calendar weeks for 2021 are defined according to the international ISO standard. That is, each calendar week starts on Monday and ends on Sunday. Even during the change of year, a new calendar week starts on Monday and ends on Sunday. The ISO standard specifies that the majority of the first calendar week (i.e., at least four days) must lie in the new year.

Table of all American calendar weeks for 2021

The following table shows all "American" calendar weeks 2021, with their start date beginning on Sunday and their end date falling on Saturday.

American calendar weeks 2021 - CW 2021
CWStart of the CWEnd of the CW
1Friday, January 1, 2021Saturday, January 2, 2021
2Sunday, January 3, 2021Saturday, January 9, 2021
3Sunday, January 10, 2021Saturday, January 16, 2021
4Sunday, January 17, 2021Saturday, January 23, 2021
5Sunday, January 24, 2021Saturday, January 30, 2021
6Sunday, January 31, 2021Saturday, February 6, 2021
7Sunday, February 7, 2021Saturday, February 13, 2021
8Sunday, February 14, 2021Saturday, February 20, 2021
9Sunday, February 21, 2021Saturday, February 27, 2021
10Sunday, February 28, 2021Saturday, March 6, 2021
11Sunday, March 7, 2021Saturday, March 13, 2021
12Sunday, March 14, 2021Saturday, March 20, 2021
13Sunday, March 21, 2021Saturday, March 27, 2021
14Sunday, March 28, 2021Saturday, April 3, 2021
15Sunday, April 4, 2021Saturday, April 10, 2021
16Sunday, April 11, 2021Saturday, April 17, 2021
17Sunday, April 18, 2021Saturday, April 24, 2021
18Sunday, April 25, 2021Saturday, May 1, 2021
19Sunday, May 2, 2021Saturday, May 8, 2021
20Sunday, May 9, 2021Saturday, May 15, 2021
21Sunday, May 16, 2021Saturday, May 22, 2021
22Sunday, May 23, 2021Saturday, May 29, 2021
23Sunday, May 30, 2021Saturday, June 5, 2021
24Sunday, June 6, 2021Saturday, June 12, 2021
25Sunday, June 13, 2021Saturday, June 19, 2021
26Sunday, June 20, 2021Saturday, June 26, 2021
27Sunday, June 27, 2021Saturday, July 3, 2021
28Sunday, July 4, 2021Saturday, July 10, 2021
29Sunday, July 11, 2021Saturday, July 17, 2021
30Sunday, July 18, 2021Saturday, July 24, 2021
31Sunday, July 25, 2021Saturday, July 31, 2021
32Sunday, August 1, 2021Saturday, August 7, 2021
33Sunday, August 8, 2021Saturday, August 14, 2021
34Sunday, August 15, 2021Saturday, August 21, 2021
35Sunday, August 22, 2021Saturday, August 28, 2021
36Sunday, August 29, 2021Saturday, September 4, 2021
37Sunday, September 5, 2021Saturday, September 11, 2021
38Sunday, September 12, 2021Saturday, September 18, 2021
39Sunday, September 19, 2021Saturday, September 25, 2021
40Sunday, September 26, 2021Saturday, October 2, 2021
41Sunday, October 3, 2021Saturday, October 9, 2021
42Sunday, October 10, 2021Saturday, October 16, 2021
43Sunday, October 17, 2021Saturday, October 23, 2021
44Sunday, October 24, 2021Saturday, October 30, 2021
45Sunday, October 31, 2021Saturday, November 6, 2021
46Sunday, November 7, 2021Saturday, November 13, 2021
47Sunday, November 14, 2021Saturday, November 20, 2021
48Sunday, November 21, 2021Saturday, November 27, 2021
49Sunday, November 28, 2021Saturday, December 4, 2021
50Sunday, December 5, 2021Saturday, December 11, 2021
51Sunday, December 12, 2021Saturday, December 18, 2021
52Sunday, December 19, 2021Saturday, December 25, 2021
53Sunday, December 26, 2021Friday, December 31, 2021

The "American" calendar weeks for 2021 are used in the USA, Canada and most Latin American countries, Australia, Japan, Israel, South Korea and others. Unlike the otherwise internationally standardised ISO weeks, the American calendar weeks start on Sundays instead of Mondays and end on Saturdays. However, the first calendar week always begins on the 1st of January and the last always ends on the 31st of December. These two weeks can have fewer than seven days. There are always 53 calendar weeks, except in a leap year where 31st December is a Sunday. As a result, such a year will have 54 calendar weeks.

Calculation of any calendar weeks 2021

Source information

As source for the information in the "Week Numbers" category, we have used in particular:

Last update on September 27, 2021

The pages of the "Week Numbers" category were last editorially reviewed by Michael Mühl on September 27, 2021. They all correspond to the current status.

Previous changes on June 25, 2020