| Millennium: | 1st millennium |
|---|---|
| Centuries: | |
| Decades: | |
| Years: |
| Gregorian calendar | 812 DCCCXII |
| Ab urbe condita | 1565 |
| Armenian calendar | 261 ԹՎ ՄԿԱ |
| Assyrian calendar | 5562 |
| Bengali calendar | 219 |
| Berber calendar | 1762 |
| Buddhist calendar | 1356 |
| Burmese calendar | 174 |
| Byzantine calendar | 6320–6321 |
| Chinese calendar |
辛卯年 (Metal Rabbit) 3508 or 3448 — to — 壬辰年 (Water Dragon) 3509 or 3449 |
| Coptic calendar | 528–529 |
| Discordian calendar | 1978 |
| Ethiopian calendar | 804–805 |
| Hebrew calendar | 4572–4573 |
| Hindu calendars | |
| - Vikram Samvat | 868–869 |
| - Shaka Samvat | 733–734 |
| - Kali Yuga | 3912–3913 |
| Holocene calendar | 10812 |
| Iranian calendar | 190–191 |
| Islamic calendar | 196–197 |
| Japanese calendar |
Kōnin 3 (弘仁3年) |
| Javanese calendar | 708–709 |
| Julian calendar | 812 DCCCXII |
| Korean calendar | 3145 |
| Minguo calendar | 1100 before ROC 民前1100年 |
| Nanakshahi calendar | −656 |
| Seleucid era | 1123/1124 AG |
| Thai solar calendar | 1354–1355 |
Year 812 (DCCCXII) was a leap year starting on Thursday (link will display the full calendar) of the Julian calendar.