| Millennium: | 2nd millennium |
|---|---|
| Centuries: | 10th century – 11th century – 12th century |
| Decades: | 990s 1000s 1010s – 1020s – 1030s 1040s 1050s |
| Years: | 1018 1019 1020 – 1021 – 1022 1023 1024 |
| 1021 by topic | |
| Lists of leaders | |
| State 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 |
| Bahá'í calendar | -823–-822 |
| Bengali calendar | 428 |
| Berber calendar | 1971 |
| English Regnal year | N/A |
| Buddhist calendar | 1565 |
| Burmese calendar | 383 |
| Byzantine calendar | 6529–6530 |
| Chinese calendar | 庚申年十二月十六日 (3657/3717-12-16) — to —
辛酉年十一月廿五日(3658/3718-11-25) |
| Coptic calendar | 737–738 |
| Ethiopian calendar | 1013–1014 |
| Hebrew calendar | 4781–4782 |
| Hindu calendars | |
| - Vikram Samvat | 1077–1078 |
| - Shaka Samvat | 943–944 |
| - Kali Yuga | 4122–4123 |
| Holocene calendar | 11021 |
| Iranian calendar | 399–400 |
| Islamic calendar | 411–412 |
| Japanese calendar | |
| Korean calendar | 3354 |
| Minguo calendar | 891 before ROC 民前891年 |
| Thai solar calendar | 1564 |
Year 1021 (MXXI) was a common year starting on Sunday (link will display the full calendar) of the Julian calendar.