| Millennium: | 1st millennium |
|---|---|
| Centuries: | 2nd century – 3rd century – 4th century |
| Decades: | 220s 230s 240s – 250s – 260s 270s 280s |
| Years: | 254 255 256 – 257 – 258 259 260 |
| 257 by topic | |
| Politics | |
| State leaders – Sovereign states | |
| Birth and death categories | |
| Births – Deaths | |
| Establishment and disestablishment categories | |
| Establishments – Disestablishments | |
| Gregorian calendar | 257 CCLVII |
| Ab urbe condita | 1010 |
| Armenian calendar | N/A |
| Assyrian calendar | 5007 |
| Bahá'í calendar | -1587–-1586 |
| Bengali calendar | -336 |
| Berber calendar | 1207 |
| English Regnal year | N/A |
| Buddhist calendar | 801 |
| Burmese calendar | -381 |
| Byzantine calendar | 5765–5766 |
| Chinese calendar | 丙子年十一月廿九日 (2893/2953-11-29) — to —
丁丑年十一月初九日(2894/2954-11-9) |
| Coptic calendar | -27–-26 |
| Ethiopian calendar | 249–250 |
| Hebrew calendar | 4017–4018 |
| Hindu calendars | |
| - Vikram Samvat | 313–314 |
| - Shaka Samvat | 179–180 |
| - Kali Yuga | 3358–3359 |
| Holocene calendar | 10257 |
| Iranian calendar | 365 BP – 364 BP |
| Islamic calendar | 376 BH – 375 BH |
| Japanese calendar | |
| Korean calendar | 2590 |
| Minguo calendar | 1655 before ROC 民前1655年 |
| Thai solar calendar | 800 |
Year 257 (CCLVII) was a common year starting on Thursday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Valerianus and Gallienus (or, less frequently, year 1010 Ab urbe condita). The denomination 257 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.