| Millennium: | 1st millennium BC |
|---|---|
| Centuries: | 3rd century BC – 2nd century BC – 1st century BC |
| Decades: | 130s BC 120s BC 110s BC – 100s BC – 90s BC 80s BC 70s BC |
| Years: | 112 BC 111 BC 110 BC – 109 BC – 108 BC 107 BC 106 BC |
| 109 BC by topic | |
| Politics | |
| State leaders – Sovereign states | |
| Birth and death categories | |
| Births – Deaths | |
| Establishments and disestablishments categories | |
| Establishments – Disestablishments | |
| Gregorian calendar | 109 BC |
| Ab urbe condita | 645 |
| Armenian calendar | N/A |
| Assyrian calendar | 4642 |
| Bahá'í calendar | -1952–-1951 |
| Bengali calendar | -701 |
| Berber calendar | 842 |
| English Regnal year | N/A |
| Buddhist calendar | 436 |
| Burmese calendar | -746 |
| Byzantine calendar | 5400–5401 |
| Chinese calendar | 辛未年 (2528/2588) — to —
壬申年(2529/2589) |
| Coptic calendar | -392–-391 |
| Ethiopian calendar | -116–-115 |
| Hebrew calendar | 3652–3653 |
| Hindu calendars | |
| - Vikram Samvat | -52–-51 |
| - Shaka Samvat | N/A |
| - Kali Yuga | 2993–2994 |
| Holocene calendar | 9892 |
| Iranian calendar | 730 BP – 729 BP |
| Islamic calendar | 752 BH – 751 BH |
| Japanese calendar | |
| Korean calendar | 2225 |
| Minguo calendar | 2020 before ROC 民前2020年 |
| Thai solar calendar | 435 |
Year 109 BC was a year of the pre-Julian Roman calendar. At the time it was known as the Year of the Consulship of Numidicus and Silanus (or, less frequently, year 645 Ab urbe condita). The denomination 109 BC 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.