|Centuries:||3rd century – 4th century – 5th century|
|Decades:||270s 280s 290s – 300s – 310s 320s 330s|
|Years:||304 305 306 – 307 – 308 309 310|
|307 by topic|
|State leaders – Sovereign states|
|Birth and death categories|
|Births – Deaths|
|Establishment and disestablishment categories|
|Establishments – Disestablishments|
|Ab urbe condita||1060|
|Chinese calendar||丙寅年 (Fire Tiger)
3003 or 2943
— to —
丁卯年 (Fire Rabbit)
3004 or 2944
|- Vikram Samvat||363–364|
|- Shaka Samvat||229–230|
|- Kali Yuga||3408–3409|
|Iranian calendar||315 BP – 314 BP|
|Islamic calendar||325 BH – 324 BH|
|Minguo calendar||1605 before ROC
|Seleucid era||618/619 AG|
|Thai solar calendar||849–850|
|Wikimedia Commons has media related to 307.|
Year 307 (CCCVII) was a common year starting on Wednesday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Valerius and Constantius (or, less frequently, year 1060 Ab urbe condita). The denomination 307 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.
- Constantine is made a Caesar by Galerius and returns to Britain.
- March 31 – After divorcing his wife Minervina, Constantine the Great marries Fausta Flavia Maxima, the daughter of the retired co-emperor Maximian.
- Constantine I established his capital in Augusta Treverorum (Trier). He begins a major expansion of the city, strengthening the walls with fortified gates, building a palace complex and the Imperial Baths.
- September 16 – Severus II is captured and imprisoned at Tres Tabernae. After Emperor Galerius unsuccessfully invades Italy to suppress Maxentius, he is executed (or forced to commit suicide).
- January 8 – Emperor Jin Huidi dies after a 16-year reign in which eight dukes of the imperial family have conducted a civil war (War of the Eight Princes) against each other in a struggle for power. Jin Huaidi, age 23, succeeds his father and becomes third emperor of the Jin Dynasty.
- January 8 – Jin Huidi, Chinese Emperor of the Jin Dynasty (b. 259)
- September 16 – Severus II, deposed Roman Emperor (murdered)
- Tuoba Luguan, chieftain of the Tuoba clan (China)