| Centuries: | 4th century BC - 3rd century BC - 2nd century BC |
| Decades: | 250s BC 240s BC 230s BC - 220s BC - 210s BC 200s BC 190s BC |
| Years: | 224 BC 223 BC 222 BC - 221 BC - 220 BC 219 BC 218 BC |
| 221 BC by topic | |
| Politics | |
| State leaders - Sovereign states | |
| Birth and death categories | |
| Births - Deaths | |
| Establishments and disestablishments categories | |
| Establishments - Disestablishments | |
| Gregorian calendar | 221 BC |
| Ab urbe condita | 533 |
| Armenian calendar | N/A |
| Bahá'í calendar | -2064 – -2063 |
| Berber calendar | 730 |
| Buddhist calendar | 324 |
| Burmese calendar | -858 |
| Chinese calendar | 2416/2476 ([[Sexagenary cycle|]]年) — to —
2417/2477([[Sexagenary cycle|]]年) |
| Coptic calendar | -504 – -503 |
| Ethiopian calendar | -228 – -227 |
| Hebrew calendar | 3540 – 3541 |
| Hindu calendars | |
| - Vikram Samvat | -165 – -164 |
| - Shaka Samvat | N/A |
| - Kali Yuga | 2881 – 2882 |
| Holocene calendar | 9780 |
| Iranian calendar | 842 BP – 841 BP |
| Islamic calendar | 868 BH – 867 BH |
| Japanese calendar | |
| Korean calendar | 2113 |
| Thai solar calendar | 323 |