1231
| Years | 
|---|
| Millennium | 
| 2nd millennium | 
| Centuries | 
| Decades | 
| Years | 
| 1231 by topic | 
|---|
| Leaders | 
| 
 | 
| Birth and death categories | 
| Births – Deaths | 
| Establishments and disestablishments categories | 
| Establishments – Disestablishments | 
| Art and literature | 
| 1231 in poetry | 
| Gregorian calendar | 1231 MCCXXXI | 
| Ab urbe condita | 1984 | 
| Armenian calendar | 680 ԹՎ ՈՁ | 
| Assyrian calendar | 5981 | 
| Balinese saka calendar | 1152–1153 | 
| Bengali calendar | 637–638 | 
| Berber calendar | 2181 | 
| English Regnal year | 15 Hen. 3 – 16 Hen. 3 | 
| Buddhist calendar | 1775 | 
| Burmese calendar | 593 | 
| Byzantine calendar | 6739–6740 | 
| Chinese calendar | 庚寅年 (Metal Tiger) 3928 or 3721 — to — 辛卯年 (Metal Rabbit) 3929 or 3722 | 
| Coptic calendar | 947–948 | 
| Discordian calendar | 2397 | 
| Ethiopian calendar | 1223–1224 | 
| Hebrew calendar | 4991–4992 | 
| Hindu calendars | |
| - Vikram Samvat | 1287–1288 | 
| - Shaka Samvat | 1152–1153 | 
| - Kali Yuga | 4331–4332 | 
| Holocene calendar | 11231 | 
| Igbo calendar | 231–232 | 
| Iranian calendar | 609–610 | 
| Islamic calendar | 628–629 | 
| Japanese calendar | Kangi 3 (寛喜3年) | 
| Javanese calendar | 1140–1141 | 
| Julian calendar | 1231 MCCXXXI | 
| Korean calendar | 3564 | 
| Minguo calendar | 681 before ROC 民前681年 | 
| Nanakshahi calendar | −237 | 
| Thai solar calendar | 1773–1774 | 
| Tibetan calendar | 阳金虎年 (male Iron-Tiger) 1357 or 976 or 204 — to — 阴金兔年 (female Iron-Rabbit) 1358 or 977 or 205 | 
Year 1231 (MCCXXXI) was a common year starting on Wednesday of the Julian calendar.