| Millennium: | 1st millennium BC |
|---|---|
| Centuries: | 2nd century BC – 1st century BC – 1st century |
| Decades: | 40s BC 30s BC 20s BC – 10s BC – 0s BC 0s 10s |
| Years: | 21 BC 20 BC 19 BC – 18 BC – 17 BC 16 BC 15 BC |
| 18 BC by topic | |
| Politics | |
| State leaders – Sovereign states | |
| Birth and death categories | |
| Births – Deaths | |
| Establishments and disestablishments categories | |
| Establishments – Disestablishments | |
| Gregorian calendar | 18 BC |
| Ab urbe condita | 736 |
| Armenian calendar | N/A |
| Bahá'í calendar | -1861 – -1860 |
| Bengali calendar | -610 |
| Berber calendar | 933 |
| Buddhist calendar | 527 |
| Burmese calendar | -655 |
| Byzantine calendar | 5491 – 5492 |
| Chinese calendar | 壬寅年 (2619/2679) — to —
癸卯年(2620/2680) |
| Coptic calendar | -301 – -300 |
| Ethiopian calendar | -25 – -24 |
| Hebrew calendar | 3743 – 3744 |
| Hindu calendars | |
| - Bikram Samwat | 39 – 40 |
| - Shaka Samvat | N/A |
| - Kali Yuga | 3084 – 3085 |
| Holocene calendar | 9983 |
| Iranian calendar | 639 BP – 638 BP |
| Islamic calendar | 659 BH – 658 BH |
| Japanese calendar | |
| Korean calendar | 2316 |
| Thai solar calendar | 526 |
Year 18 BC was a common year starting on Thursday (link will display the full calendar) of the Julian calendar.