|Ab urbe condita||2774|
|Balinese saka calendar||1942–1943|
|British Regnal year||N/A|
|Chinese calendar||庚子年 (Metal Rat)|
4717 or 4657
— to —
辛丑年 (Metal Ox)
4718 or 4658
|- Vikram Samvat||2077–2078|
|- Shaka Samvat||1942–1943|
|- Kali Yuga||5121–5122|
|Japanese calendar||Heisei 33|
|Julian calendar||Gregorian minus 13 days|
|Minguo calendar||ROC 110|
|Thai solar calendar||2564|
2147 or 1766 or 994
— to —
2148 or 1767 or 995
|Unix time||1609459200 – 1640995199|
|Wikimedia Commons has media related to 2021.|
2021 (MMXXI) will be a common year starting on Friday of the Gregorian calendar, the 2021st year of the Common Era (CE) and Anno Domini (AD) designations, the 21st year of the 3rd millennium, the 21st year of the 21st century, and the 2nd year of the 2020s decade.
Predicted and scheduled events
- March 30 – The James Webb Space Telescope is scheduled to be launched after being delayed several times.
- May 26 – The shortest total lunar eclipse of the 21st century is expected to occur, lasting just 14 minutes and 30 seconds long.
- November 2 - the 2021 United States elections will choose 2 state governors and various state and local officials.
- India hopes to conduct its first human spaceflight in 2021.
- Brood X, the largest brood of North American seventeen-year cicadas, will emerge.
- Costa Rica has pledged to become a completely carbon-neutral nation by this date. The target date has been set by President Óscar Arias.
- Costa Rica has pledged to ban "single use" plastic products. The target date has been set by President Luis Guillermo Solís.
- Amtrak's Avelia Liberty trains are expected to enter service in 2021.
- "New launch date for James Webb Space Telescope". European Space Agency. June 28, 2018. Retrieved July 15, 2018.
- "India's first manned space mission likely to be accomplished in 2021 now". www.merinews.com.
- National Geographic, February 2008
- "Costa Rica launches quest to replace most single-use plastic by 2021". 6 June 2017.