| Centuries: | 4th century · 5th century · 6th century |
| Decades: | 370s 380s 390s 400s 410s 420s 430s |
| Years: | 400 401 402 403 404 405 406 |
| 403 by topic | |
| Politics | |
| State leaders – Sovereign states | |
| Birth and death categories | |
| Births – Deaths | |
| Establishment and disestablishment categories | |
| Establishments – Disestablishments | |
| Gregorian calendar | 403 CDIII |
| Ab urbe condita | 1156 |
| Armenian calendar | N/A |
| Bahá'í calendar | -1441 – -1440 |
| Bengali calendar | -190 |
| Berber calendar | 1353 |
| Buddhist calendar | 947 |
| Burmese calendar | -235 |
| Byzantine calendar | 5911 – 5912 |
| Chinese calendar | 壬寅年十一月廿二日 (3039/3099-11-22) — to —
癸卯年十二月初二日(3040/3100-12-2) |
| Coptic calendar | 119 – 120 |
| Ethiopian calendar | 395 – 396 |
| Hebrew calendar | 4163 – 4164 |
| Hindu calendars | |
| - Bikram Samwat | 459 – 460 |
| - Shaka Samvat | 325 – 326 |
| - Kali Yuga | 3504 – 3505 |
| Holocene calendar | 10403 |
| Iranian calendar | 219 BP – 218 BP |
| Islamic calendar | 226 BH – 225 BH |
| Japanese calendar | |
| Korean calendar | 2736 |
| Thai solar calendar | 946 |