| Millennium: | 1st millennium |
|---|---|
| Centuries: | 8th century – 9th century – 10th century |
| Decades: | 790s 800s 810s – 820s – 830s 840s 850s |
| Years: | 820 821 822 – 823 – 824 825 826 |
| 823 by topic | |
| Politics | |
| State leaders – Sovereign states | |
| Birth and death categories | |
| Births – Deaths | |
| Establishment and disestablishment categories | |
| Establishments – Disestablishments | |
| Gregorian calendar | 823 DCCCXXIII |
| Ab urbe condita | 1576 |
| Armenian calendar | 272 ԹՎ ՄՀԲ |
| Bahá'í calendar | -1021 – -1020 |
| Bengali calendar | 230 |
| Berber calendar | 1773 |
| Buddhist calendar | 1367 |
| Burmese calendar | 185 |
| Byzantine calendar | 6331 – 6332 |
| Chinese calendar | 壬寅年十一月十六日 (3459/3519-11-16) — to —
癸卯年十一月廿六日(3460/3520-11-26) |
| Coptic calendar | 539 – 540 |
| Ethiopian calendar | 815 – 816 |
| Hebrew calendar | 4583 – 4584 |
| Hindu calendars | |
| - Bikram Samwat | 879 – 880 |
| - Shaka Samvat | 745 – 746 |
| - Kali Yuga | 3924 – 3925 |
| Holocene calendar | 10823 |
| Iranian calendar | 201 – 202 |
| Islamic calendar | 207 – 208 |
| Japanese calendar | |
| Korean calendar | 3156 |
| Thai solar calendar | 1366 |