Week number 40 (Week 40) 2021

Updated on by Michael Mühl

Week number 40 of the current year 2021 is defined as follows:

European and Asian calculation

Mainly in Europe and Asia, the international ISO 8601 definition is used for counting calendar weeks:

Week number 40/2021

Monday, October  4, 2021

Sunday, October 10, 2021

ISO-Notation: 2021‑W40

American calculation

In the USA, Canada and most Latin American countries, Australia as well as in Japan, Israel, South Korea and others, the following definition of week 40 applies:

Week number 40/2021

Sunday, September 26, 2021

Saturday, October  2, 2021

The date of the calendar week 40 (Week 40) in the past and coming years

The following table provides an overview of the calendar week 40 for each year. The beginning of the calendar week 40 and its end are shown according to the two most commonly used definitions of calendar weeks worldwide. The first is the international ISO standard for week 40, referred to here as the "European" calculation method. It is mainly used in Europe and Asia. On the other hand, the "American" calculation method for weeks is listed, which is mainly used in North and South America, Australia and e.g. Japan.

Week number 40
Year Calculation
method
Start of week 40End of week 40ISO name
2011 European Monday, October  3, 2011Sunday, October  9, 20112011‑W40
American Sunday, September 25, 2011Saturday, October  1, 2011-
2012 European Monday, October  1, 2012Sunday, October  7, 20122012‑W40
American Sunday, September 30, 2012Saturday, October  6, 2012-
2013 European Monday, September 30, 2013Sunday, October  6, 20132013‑W40
American Sunday, September 29, 2013Saturday, October  5, 2013-
2014 European Monday, September 29, 2014Sunday, October  5, 20142014‑W40
American Sunday, September 28, 2014Saturday, October  4, 2014-
2015 European Monday, September 28, 2015Sunday, October  4, 20152015‑W40
American Sunday, September 27, 2015Saturday, October  3, 2015-
2016 European Monday, October  3, 2016Sunday, October  9, 20162016‑W40
American Sunday, September 25, 2016Saturday, October  1, 2016-
2017 European Monday, October  2, 2017Sunday, October  8, 20172017‑W40
American Sunday, October  1, 2017Saturday, October  7, 2017-
2018 European Monday, October  1, 2018Sunday, October  7, 20182018‑W40
American Sunday, September 30, 2018Saturday, October  6, 2018-
2019 European Monday, September 30, 2019Sunday, October  6, 20192019‑W40
American Sunday, September 29, 2019Saturday, October  5, 2019-
2020 European Monday, September 28, 2020Sunday, October  4, 20202020‑W40
American Sunday, September 27, 2020Saturday, October  3, 2020-
2021 European Monday, October  4, 2021Sunday, October 10, 20212021‑W40
American Sunday, September 26, 2021Saturday, October  2, 2021-
2022 European Monday, October  3, 2022Sunday, October  9, 20222022‑W40
American Sunday, September 25, 2022Saturday, October  1, 2022-
2023 European Monday, October  2, 2023Sunday, October  8, 20232023‑W40
American Sunday, October  1, 2023Saturday, October  7, 2023-
2024 European Monday, September 30, 2024Sunday, October  6, 20242024‑W40
American Sunday, September 29, 2024Saturday, October  5, 2024-
2025 European Monday, September 29, 2025Sunday, October  5, 20252025‑W40
American Sunday, September 28, 2025Saturday, October  4, 2025-
2026 European Monday, September 28, 2026Sunday, October  4, 20262026‑W40
American Sunday, September 27, 2026Saturday, October  3, 2026-
2027 European Monday, October  4, 2027Sunday, October 10, 20272027‑W40
American Sunday, September 26, 2027Saturday, October  2, 2027-
2028 European Monday, October  2, 2028Sunday, October  8, 20282028‑W40
American Sunday, September 24, 2028Saturday, September 30, 2028-
2029 European Monday, October  1, 2029Sunday, October  7, 20292029‑W40
American Sunday, September 30, 2029Saturday, October  6, 2029-
2030 European Monday, September 30, 2030Sunday, October  6, 20302030‑W40
American Sunday, September 29, 2030Saturday, October  5, 2030-
2031 European Monday, September 29, 2031Sunday, October  5, 20312031‑W40
American Sunday, September 28, 2031Saturday, October  4, 2031-

Determine week 40 or other calendar weeks in the calculator

In the calendar week calculator, the entry for the European ISO calendar week 40 is preset. Of course, you can also enter other values here to determine the date of the beginning of the week or the end of the week.

Calendar week calculator for other years

For calendar years further back or in the future, you will find the beginning and end of the corresponding calendar week in the Calendar week calculator.

 

Source information

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

Last update on June 19, 2021

The pages of the "Week Numbers" category were last editorially reviewed by Michael Mühl on June 19, 2021. They all correspond to the current status.

Previous changes on June 25, 2020