Week Number Calculator

Calendar weeks 2021 - CW 2021

Thema Week Numbers ﹣ Calendar weeks 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 CW ISO-Name
CW 1Monday, January 4, 2021Sunday, January 10, 20212021‑W01
CW 2Monday, January 11, 2021Sunday, January 17, 20212021‑W02
CW 3Monday, January 18, 2021Sunday, January 24, 20212021‑W03
CW 4Monday, January 25, 2021Sunday, January 31, 20212021‑W04
CW 5Monday, February 1, 2021Sunday, February 7, 20212021‑W05
CW 6Monday, February 8, 2021Sunday, February 14, 20212021‑W06
CW 7Monday, February 15, 2021Sunday, February 21, 20212021‑W07
CW 8Monday, February 22, 2021Sunday, February 28, 20212021‑W08
CW 9Monday, March 1, 2021Sunday, March 7, 20212021‑W09
CW 10Monday, March 8, 2021Sunday, March 14, 20212021‑W10
CW 11Monday, March 15, 2021Sunday, March 21, 20212021‑W11
CW 12Monday, March 22, 2021Sunday, March 28, 20212021‑W12
CW 13Monday, March 29, 2021Sunday, April 4, 20212021‑W13
CW 14Monday, April 5, 2021Sunday, April 11, 20212021‑W14
CW 15Monday, April 12, 2021Sunday, April 18, 20212021‑W15
CW 16Monday, April 19, 2021Sunday, April 25, 20212021‑W16
CW 17Monday, April 26, 2021Sunday, May 2, 20212021‑W17
CW 18Monday, May 3, 2021Sunday, May 9, 20212021‑W18
CW 19Monday, May 10, 2021Sunday, May 16, 20212021‑W19
CW 20Monday, May 17, 2021Sunday, May 23, 20212021‑W20
CW 21Monday, May 24, 2021Sunday, May 30, 20212021‑W21
CW 22Monday, May 31, 2021Sunday, June 6, 20212021‑W22
CW 23Monday, June 7, 2021Sunday, June 13, 20212021‑W23
CW 24Monday, June 14, 2021Sunday, June 20, 20212021‑W24
CW 25Monday, June 21, 2021Sunday, June 27, 20212021‑W25
CW 26Monday, June 28, 2021Sunday, July 4, 20212021‑W26
CW 27Monday, July 5, 2021Sunday, July 11, 20212021‑W27
CW 28Monday, July 12, 2021Sunday, July 18, 20212021‑W28
CW 29Monday, July 19, 2021Sunday, July 25, 20212021‑W29
CW 30Monday, July 26, 2021Sunday, August 1, 20212021‑W30
CW 31Monday, August 2, 2021Sunday, August 8, 20212021‑W31
CW 32Monday, August 9, 2021Sunday, August 15, 20212021‑W32
CW 33Monday, August 16, 2021Sunday, August 22, 20212021‑W33
CW 34Monday, August 23, 2021Sunday, August 29, 20212021‑W34
CW 35Monday, August 30, 2021Sunday, September 5, 20212021‑W35
CW 36Monday, September 6, 2021Sunday, September 12, 20212021‑W36
CW 37Monday, September 13, 2021Sunday, September 19, 20212021‑W37
CW 38Monday, September 20, 2021Sunday, September 26, 20212021‑W38
CW 39Monday, September 27, 2021Sunday, October 3, 20212021‑W39
CW 40Monday, October 4, 2021Sunday, October 10, 20212021‑W40
CW 41Monday, October 11, 2021Sunday, October 17, 20212021‑W41
CW 42Monday, October 18, 2021Sunday, October 24, 20212021‑W42
CW 43Monday, October 25, 2021Sunday, October 31, 20212021‑W43
CW 44Monday, November 1, 2021Sunday, November 7, 20212021‑W44
CW 45Monday, November 8, 2021Sunday, November 14, 20212021‑W45
CW 46Monday, November 15, 2021Sunday, November 21, 20212021‑W46
CW 47Monday, November 22, 2021Sunday, November 28, 20212021‑W47
CW 48Monday, November 29, 2021Sunday, December 5, 20212021‑W48
CW 49Monday, December 6, 2021Sunday, December 12, 20212021‑W49
CW 50Monday, December 13, 2021Sunday, December 19, 20212021‑W50
CW 51Monday, December 20, 2021Sunday, December 26, 20212021‑W51
CW 52Monday, December 27, 2021Sunday, January 2, 20222021‑W52
CW 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 July 2, 2022

The pages of the "Week Numbers" category were last editorially reviewed by Michael Mühl on July 2, 2022. They all correspond to the current status.

Previous changes on June 25, 2021