How many years did Alexander the Great rule Macedon?

Alexander the Great ruled Macedon for 13 years, from his accession in 336 BC until his death in 323 BC. He became king at about 20 years old after his father, Philip II, was assassinated.

Alexander inherited a powerful Macedonian kingdom and the leadership of the Greek alliance Philip had assembled. During his reign, he first secured control of Greece and the Balkans, then invaded the Persian Empire. His campaigns carried Macedonian power through Egypt, Persia, Central Asia, and into northwestern India.

The figure of 13 years is the conventional historical count for his reign. In precise calendar terms, his rule lasted roughly twelve years and eight months—from late 336 BC to June 323 BC—but ancient and modern regnal calculations commonly count the span as 13 years.

Alexander died in Babylon in 323 BC at the age of 32, leaving no mature successor capable of holding his empire together. After his death, his generals divided the territories in a series of struggles known as the Wars of the Diadochi. His brother Philip III and infant son Alexander IV were named successors, but neither effectively ruled the empire.