|Millennium:||1st millennium BC|
|Centuries:||6th century BC – 5th century BC – 4th century BC|
|Decades:||460s BC 450s BC 440s BC – 430s BC – 420s BC 410s BC 400s BC|
|Years:||436 BC 435 BC 434 BC – 433 BC – 432 BC 431 BC 430 BC|
|433 BC by topic|
|State leaders – Sovereign states|
|Birth and death categories|
|Births – Deaths|
|Establishments and disestablishments categories|
|Establishments – Disestablishments|
|Gregorian calendar||433 BC|
|Ab urbe condita||321|
|Bahá'í calendar||−2276 – −2275|
|English Regnal year||N/A|
|Chinese calendar||丁未年 (Fire Goat)
2264 or 2204
— to —
戊申年 (Earth Monkey)
2265 or 2205
|Coptic calendar||−716 – −715|
|Ethiopian calendar||−440 – −439|
|- Vikram Samvat||−376 – −375|
|- Shaka Samvat||N/A|
|- Kali Yuga||2669–2670|
|Igbo calendar||−1432 – −1431|
|Iranian calendar||1054 BP – 1053 BP|
|Islamic calendar||1086 BH – 1085 BH|
|Minguo calendar||2344 before ROC
|Thai solar calendar||111|
|Wikimedia Commons has media related to 433 BC.|
Year 433 BC was a year of the pre-Julian Roman calendar. At the time, it was known as the Year of the Tribunate of Vibulanus, Fidenas and Flaccinator (or, less frequently, year 321 Ab urbe condita). The denomination 433 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.
- Pericles concludes a defensive alliance with Corcyra (Corfu), the strong naval power in the Ionian Sea, which is the bitter enemy of Corinth. As a result, Athens intervenes in the dispute between Corinth and Corcyra, and, at the Battle of Sybota, a small contingent of Athenian ships play a critical role in preventing a Corinthian fleet from capturing Corcyra. Following this, Athens places Potidaea, a tributary ally of Athens but a colony of Corinth, under siege.
- The Corinthians, upset by Athens' actions, lobby Sparta to take action against Athens. This appeal is backed by Megara (which is being severely affected by Pericles' economic sanctions) and by Aegina (which is being heavily taxed by Pericles and which has been refused home rule).
- Pericles renews alliances with the Rhegium on the south west corner of Italy and Leontini in south-east Sicily, threatening Sparta's food supply route from Sicily.
- A set of sixty-five bells, from the Tomb of Marquis Yi of Zeng (Zhou dynasty) in Suixian, Hubei, is made. It is now preserved at the Hubei Provincial Museum in Wuhan.