| Centuries: | 3rd century · 4th century · 5th century |
| Decades: | 270s 280s 290s 300s 310s 320s 330s |
| Years: | 303 304 305 306 307 308 309 |
| 306 by topic | |
| Politics | |
| State leaders – Sovereign states | |
| Birth and death categories | |
| Births – Deaths | |
| Establishment and disestablishment categories | |
| Establishments – Disestablishments | |
| Gregorian calendar | 306 CCCVI |
| Ab urbe condita | 1059 |
| Armenian calendar | N/A |
| Bahá'í calendar | -1538 – -1537 |
| Bengali calendar | -287 |
| Berber calendar | 1256 |
| Buddhist calendar | 850 |
| Burmese calendar | -332 |
| Byzantine calendar | 5814 – 5815 |
| Chinese calendar | 乙丑年十二月初一日 (2942/3002-12-1) — to —
丙寅年十一月初十日(2943/3003-11-10) |
| Coptic calendar | 22 – 23 |
| Ethiopian calendar | 298 – 299 |
| Hebrew calendar | 4066 – 4067 |
| Hindu calendars | |
| - Bikram Samwat | 362 – 363 |
| - Shaka Samvat | 228 – 229 |
| - Kali Yuga | 3407 – 3408 |
| Holocene calendar | 10306 |
| Iranian calendar | 316 BP – 315 BP |
| Islamic calendar | 326 BH – 325 BH |
| Japanese calendar | |
| Korean calendar | 2639 |
| Thai solar calendar | 849 |