| Centuries: | 3rd century · 4th century · 5th century |
| Decades: | 310s 320s 330s 340s 350s 360s 370s |
| Years: | 339 340 341 342 343 344 345 |
| 342 by topic | |
| Politics | |
| State leaders – Sovereign states | |
| Birth and death categories | |
| Births – Deaths | |
| Establishment and disestablishment categories | |
| Establishments – Disestablishments | |
| Gregorian calendar | 342 CCCXLII |
| Ab urbe condita | 1095 |
| Armenian calendar | N/A |
| Bahá'í calendar | -1502 – -1501 |
| Bengali calendar | -251 |
| Berber calendar | 1292 |
| Buddhist calendar | 886 |
| Burmese calendar | -296 |
| Byzantine calendar | 5850 – 5851 |
| Chinese calendar | 辛丑年十二月初八日 (2978/3038-12-8) — to —
壬寅年十一月十八日(2979/3039-11-18) |
| Coptic calendar | 58 – 59 |
| Ethiopian calendar | 334 – 335 |
| Hebrew calendar | 4102 – 4103 |
| Hindu calendars | |
| - Bikram Samwat | 398 – 399 |
| - Shaka Samvat | 264 – 265 |
| - Kali Yuga | 3443 – 3444 |
| Holocene calendar | 10342 |
| Iranian calendar | 280 BP – 279 BP |
| Islamic calendar | 289 BH – 288 BH |
| Japanese calendar | |
| Korean calendar | 2675 |
| Thai solar calendar | 885 |