891
| Years | 
|---|
| Millennium | 
| 1st millennium | 
| Centuries | 
| Decades | 
| Years | 
| 891 by topic | 
|---|
| Leaders | 
| Categories | 
| 
 | 
| Gregorian calendar | 891 DCCCXCI | 
| Ab urbe condita | 1644 | 
| Armenian calendar | 340 ԹՎ ՅԽ | 
| Assyrian calendar | 5641 | 
| Balinese saka calendar | 812–813 | 
| Bengali calendar | 297–298 | 
| Berber calendar | 1841 | 
| Buddhist calendar | 1435 | 
| Burmese calendar | 253 | 
| Byzantine calendar | 6399–6400 | 
| Chinese calendar | 庚戌年 (Metal Dog) 3588 or 3381 — to — 辛亥年 (Metal Pig) 3589 or 3382 | 
| Coptic calendar | 607–608 | 
| Discordian calendar | 2057 | 
| Ethiopian calendar | 883–884 | 
| Hebrew calendar | 4651–4652 | 
| Hindu calendars | |
| - Vikram Samvat | 947–948 | 
| - Shaka Samvat | 812–813 | 
| - Kali Yuga | 3991–3992 | 
| Holocene calendar | 10891 | 
| Iranian calendar | 269–270 | 
| Islamic calendar | 277–278 | 
| Japanese calendar | Kanpyō 3 (寛平3年) | 
| Javanese calendar | 789–790 | 
| Julian calendar | 891 DCCCXCI | 
| Korean calendar | 3224 | 
| Minguo calendar | 1021 before ROC 民前1021年 | 
| Nanakshahi calendar | −577 | 
| Seleucid era | 1202/1203 AG | 
| Thai solar calendar | 1433–1434 | 
| Tibetan calendar | 阳金狗年 (male Iron-Dog) 1017 or 636 or −136 — to — 阴金猪年 (female Iron-Pig) 1018 or 637 or −135 | 
Year 891 (DCCCXCI) was a common year starting on Friday of the Julian calendar.