| Millennium: | 2nd millennium |
|---|---|
| Centuries: | |
| Decades: | |
| Years: |
| 1021 by topic |
|---|
| Leaders |
| Birth and death categories |
| Births – Deaths |
| Establishments and disestablishments categories |
| Establishments – Disestablishments |
| Gregorian calendar | 1021 MXXI |
| Ab urbe condita | 1774 |
| Armenian calendar | 470 ԹՎ ՆՀ |
| Assyrian calendar | 5771 |
| Balinese saka calendar | 942–943 |
| Bengali calendar | 428 |
| Berber calendar | 1971 |
| English Regnal year | N/A |
| Buddhist calendar | 1565 |
| Burmese calendar | 383 |
| Byzantine calendar | 6529–6530 |
| Chinese calendar | 庚申年 (Metal Monkey) 3718 or 3511 — to — 辛酉年 (Metal Rooster) 3719 or 3512 |
| Coptic calendar | 737–738 |
| Discordian calendar | 2187 |
| Ethiopian calendar | 1013–1014 |
| Hebrew calendar | 4781–4782 |
| Hindu calendars | |
| - Vikram Samvat | 1077–1078 |
| - Shaka Samvat | 942–943 |
| - Kali Yuga | 4121–4122 |
| Holocene calendar | 11021 |
| Igbo calendar | 21–22 |
| Iranian calendar | 399–400 |
| Islamic calendar | 411–412 |
| Japanese calendar | Kannin 5 / Jian 1 (治安元年) |
| Javanese calendar | 923–924 |
| Julian calendar | 1021 MXXI |
| Korean calendar | 3354 |
| Minguo calendar | 891 before ROC 民前891年 |
| Nanakshahi calendar | −447 |
| Seleucid era | 1332/1333 AG |
| Thai solar calendar | 1563–1564 |
| Tibetan calendar | 阳金猴年 (male Iron-Monkey) 1147 or 766 or −6 — to — 阴金鸡年 (female Iron-Rooster) 1148 or 767 or −5 |
Year 1021 (MXXI) was a common year starting on Sunday (link will display the full calendar) of the Julian calendar.