| Years |
|---|
| Millennium |
| 1st millennium BC |
| Centuries |
| Decades |
| Years |
| 203 BC by topic | |
| Politics | |
| State leaders – Sovereign states | |
| Birth and death categories | |
| Births – Deaths | |
| Establishments and disestablishments categories | |
| Establishments – Disestablishments | |
| Gregorian calendar | 203 BC CCII BC |
| Ab urbe condita | 551 |
| Ancient Egypt era | XXXIII dynasty, 121 |
| - Pharaoh | Ptolemy V Epiphanes, 1 |
| Ancient Greek era | 144th Olympiad, year 2 |
| Assyrian calendar | 4548 |
| Balinese saka calendar | N/A |
| Bengali calendar | −795 |
| Berber calendar | 748 |
| Buddhist calendar | 342 |
| Burmese calendar | −840 |
| Byzantine calendar | 5306–5307 |
| Chinese calendar | 丁酉年 (Fire Rooster) 2494 or 2434 — to — 戊戌年 (Earth Dog) 2495 or 2435 |
| Coptic calendar | −486 – −485 |
| Discordian calendar | 964 |
| Ethiopian calendar | −210 – −209 |
| Hebrew calendar | 3558–3559 |
| Hindu calendars | |
| - Vikram Samvat | −146 – −145 |
| - Shaka Samvat | N/A |
| - Kali Yuga | 2898–2899 |
| Holocene calendar | 9798 |
| Iranian calendar | 824 BP – 823 BP |
| Islamic calendar | 849 BH – 848 BH |
| Javanese calendar | N/A |
| Julian calendar | N/A |
| Korean calendar | 2131 |
| Minguo calendar | 2114 before ROC 民前2114年 |
| Nanakshahi calendar | −1670 |
| Seleucid era | 109/110 AG |
| Thai solar calendar | 340–341 |
| Tibetan calendar | མེ་མོ་བྱ་ལོ་ (female Fire-Bird) −76 or −457 or −1229 — to — ས་ཕོ་ཁྱི་ལོ་ (male Earth-Dog) −75 or −456 or −1228 |
Year 203 BC was a year of the pre-Julian Roman calendar.