|Millennium:||1st millennium BC|
|Centuries:||2nd century BC – 1st century BC – 1st century|
|Decades:||50s BC 40s BC 30s BC – 20s BC – 10s BC 0s BC 0s|
|Years:||28 BC 27 BC 26 BC – 25 BC – 24 BC 23 BC 22 BC|
|25 BC by topic|
|Gregorian calendar||25 BC|
|Ab urbe condita||729|
|Ancient Greek era||188th Olympiad, year 4|
|Chinese calendar||乙未年 (Wood Goat)
2672 or 2612
— to —
丙申年 (Fire Monkey)
2673 or 2613
|Coptic calendar||−308 – −307|
|Ethiopian calendar||−32 – −31|
|- Vikram Samvat||32–33|
|- Shaka Samvat||N/A|
|- Kali Yuga||3077–3078|
|Iranian calendar||646 BP – 645 BP|
|Islamic calendar||666 BH – 665 BH|
|Julian calendar||25 BC|
|Minguo calendar||1936 before ROC
|Seleucid era||287/288 AG|
|Thai solar calendar||518–519|
|Wikimedia Commons has media related to 25 BC.|
Year 25 BC was either a common year starting on Wednesday, Thursday or Friday or a leap year starting on Wednesday or Thursday (link will display the full calendar) of the Julian calendar (the sources differ, see leap year error for further information) and a leap year starting on Tuesday of the Proleptic Julian calendar. At the time, it was known as the Year of the Consulship of Augustus and Silanus (or, less frequently, year 729 Ab urbe condita). The denomination 25 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.
- Imperator Caesar Augustus becomes Consul for the ninth time. His partner is Marcus Junius Silanus.
- The temple to Neptune on the Circus Flaminius is built.
- Estimation: Rome, capital of the Roman Empire becomes the largest city of the world, taking the lead from Chang'an, capital of China.
- King Amyntas dies, Galatia becomes a Roman province. The Roman troops based there are transferred to Egypt.