| Centuries: | 2nd century - 3rd century - 4th century |
| Decades: | 220s 230s 240s - 250s - 260s 270s 280s |
| Years: | 248 249 250 - 251 - 252 253 254 |
| 251 by topic | |
| Politics | |
| State leaders - Sovereign states | |
| Birth and death categories | |
| Births - Deaths | |
| Establishment and disestablishment categories | |
| Establishments - Disestablishments | |
| Gregorian calendar | 251 CCLI |
| Ab urbe condita | 1004 |
| Armenian calendar | N/A |
| Bahá'í calendar | -1593 – -1592 |
| Berber calendar | 1201 |
| Buddhist calendar | 795 |
| Burmese calendar | -387 |
| Chinese calendar | 2887/2947-11-22 (庚午年十一月廿二日) — to —
2888/2948-12-2(辛未年十二月初二日) |
| Coptic calendar | -33 – -32 |
| Ethiopian calendar | 243 – 244 |
| Hebrew calendar | 4011 – 4012 |
| Hindu calendars | |
| - Vikram Samvat | 306 – 307 |
| - Shaka Samvat | 173 – 174 |
| - Kali Yuga | 3352 – 3353 |
| Holocene calendar | 10251 |
| Iranian calendar | 371 BP – 370 BP |
| Islamic calendar | 382 BH – 381 BH |
| Japanese calendar | |
| Korean calendar | 2584 |
| Thai solar calendar | 794 |