| Years |
|---|
| Millennium |
| 1st millennium |
| Centuries |
| Decades |
| Years |
| 240 by topic |
|---|
| Arts, history, and science |
| Countries |
|
|
| Lists of leaders |
| Birth and death categories |
| Establishments and disestablishments categories |
| Works category |
| Gregorian calendar | 240 CCXL |
| Ab urbe condita | 993 |
| Assyrian calendar | 4990 |
| Balinese saka calendar | 161–162 |
| Bengali calendar | −353 |
| Berber calendar | 1190 |
| Buddhist calendar | 784 |
| Burmese calendar | −398 |
| Byzantine calendar | 5748–5749 |
| Chinese calendar | 己未年 (Earth Goat) 2936 or 2876 — to — 庚申年 (Metal Monkey) 2937 or 2877 |
| Coptic calendar | −44 – −43 |
| Discordian calendar | 1406 |
| Ethiopian calendar | 232–233 |
| Hebrew calendar | 4000–4001 |
| Hindu calendars | |
| - Vikram Samvat | 296–297 |
| - Shaka Samvat | 161–162 |
| - Kali Yuga | 3340–3341 |
| Holocene calendar | 10240 |
| Iranian calendar | 382 BP – 381 BP |
| Islamic calendar | 394 BH – 393 BH |
| Javanese calendar | 118–119 |
| Julian calendar | 240 CCXL |
| Korean calendar | 2573 |
| Minguo calendar | 1672 before ROC 民前1672年 |
| Nanakshahi calendar | −1228 |
| Seleucid era | 551/552 AG |
| Thai solar calendar | 782–783 |
| Tibetan calendar | ས་མོ་ལུག་ལོ་ (female Earth-Sheep) 366 or −15 or −787 — to — ལྕགས་ཕོ་སྤྲེ་ལོ་ (male Iron-Monkey) 367 or −14 or −786 |

Year 240 (CCXL) was a leap year starting on Wednesday of the Julian calendar.