Year 315 BC was a year of the pre-Julian Roman calendar. At the time, it was known as the Year of the Consulship of Cursor and Philo (or, less frequently, year 439 Ab urbe condita). The denomination 315 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.
|Millennium:||1st millennium BC|
|Gregorian calendar||315 BC|
|Ab urbe condita||439|
|Ancient Egypt era||XXXIII dynasty, 9|
|- Pharaoh||Ptolemy I Soter, 9|
|Ancient Greek era||116th Olympiad, year 2|
|Balinese saka calendar||N/A|
|Chinese calendar||乙巳年 (Wood Snake)|
2382 or 2322
— to —
丙午年 (Fire Horse)
2383 or 2323
|Coptic calendar||−598 – −597|
|Ethiopian calendar||−322 – −321|
|- Vikram Samvat||−258 – −257|
|- Shaka Samvat||N/A|
|- Kali Yuga||2786–2787|
|Iranian calendar||936 BP – 935 BP|
|Islamic calendar||965 BH – 964 BH|
|Minguo calendar||2226 before ROC|
|Thai solar calendar||228–229|
−188 or −569 or −1341
— to —
−187 or −568 or −1340
- Antigonus claims authority over most of Asia, seizes the treasury at Susa and enters Babylon, where Seleucus is governor. Seleucus flees to Ptolemy in Egypt and enters into a league with him, Lysimachus (the ruler of Thrace) and Cassander, against Antigonus. This leads to the First Coalition War.
- Aristodemus of Miletus, by order of Antigonus, sails to Laconia, where he receives permission from the Spartans to recruit 8000 mercenaries. He also Meets Alexander (son of Polyperchon) and Polyperchon, thus establishing friendship between them and Antigonus 
- Polyperchon is appointed general of the Peloponnesus
- Alexander (son of Polyperchon) sails to Antigonus in Asia. They make a pact of friendship and, by order of Antigonus, Alexander sails back to the Peloponnesus
- Peithon consolidates his power base in the eastern part of the Empire.
- Antigonus drives out Cassander's Macedonian forces of occupation from the Greek islands and forms the island cities in the Aegean into the "League of the Islanders", preparatory to his invasion of Greece. His ally, the city of Rhodes, furnishes him with the necessary fleet.
- The King of Epirus, Aeacides, faces a revolt from his people and they drive him from the kingdom. His son, Phyrrhus, who is then only two years old, is saved from being killed by some faithful servants. Cassander takes control of Epirus.
- In Macedonia the port city of Thessaloniki is founded by Cassander and named after his wife Thessalonike.
- Cassander appoints Apollonides (governor of Argos) as Governor of Argos
- Apollonides (governor of Argos) initiates a raid on Arcadia during the night.
- Cassander sends Prepelaus to Alexander (son of Polyperchon) and he convinces Alexander to desert Antigonus by offering command of all the Peloponnesus and making him general of an army
- The Romans take Ferentum, a city of Apulia, and this pushes the citizens of Nuceria to end their friendship with Rome.
- The Indian king Porus, ally of Alexander The Great, is killed by Eudemus, another general of Alexander. The son of Porus, Malayketu, seizes his territory back by killing Eudemus.
- In the historical novel Funeral Games by Mary Renault, Cassander visits the Lyceum in Athens and tells Theophrastos evil slanderous lies against Alexander the Great.