| Millennium: | 1st millennium |
|---|---|
| Centuries: | 3rd century – 4th century – 5th century |
| Decades: | 270s 280s 290s – 300s – 310s 320s 330s |
| Years: | 306 307 308 – 309 – 310 311 312 |
| 309 by topic | |
| Politics | |
| State leaders – Sovereign states | |
| Birth and death categories | |
| Births – Deaths | |
| Establishment and disestablishment categories | |
| Establishments – Disestablishments | |
| Gregorian calendar | 309 CCCIX |
| Ab urbe condita | 1062 |
| Armenian calendar | N/A |
| Assyrian calendar | 5059 |
| Bahá'í calendar | -1535–-1534 |
| Bengali calendar | -284 |
| Berber calendar | 1259 |
| English Regnal year | N/A |
| Buddhist calendar | 853 |
| Burmese calendar | -329 |
| Byzantine calendar | 5817–5818 |
| Chinese calendar | 戊辰年十二月初四日 (2945/3005-12-4) — to —
己巳年十一月十四日(2946/3006-11-14) |
| Coptic calendar | 25–26 |
| Ethiopian calendar | 301–302 |
| Hebrew calendar | 4069–4070 |
| Hindu calendars | |
| - Vikram Samvat | 365–366 |
| - Shaka Samvat | 231–232 |
| - Kali Yuga | 3410–3411 |
| Holocene calendar | 10309 |
| Iranian calendar | 313 BP – 312 BP |
| Islamic calendar | 323 BH – 322 BH |
| Japanese calendar | |
| Korean calendar | 2642 |
| Minguo calendar | 1603 before ROC 民前1603年 |
| Thai solar calendar | 852 |
Year 309 (CCCIX) was a common year starting on Saturday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Licinianus and Constantius (or, less frequently, year 1062 Ab urbe condita). The denomination 309 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.