The reign of the Constantine dynasty begins with him. He unites the Roman Empire in 324, of which he is emperor for 30 years.

He became known as Constantine the Great.

Bronze coins of Constantine I are classified according to the so-called "AE" scale, which divides all bronze (AES) coins into four groups based on their size. Coins larger than 25 mm are called AE1, coins between 21 mm and 25 mm are called AE2, coins between 17 mm and 21 mm are called AE3, and coins smaller than 17 mm are called AE4. These coins are often called Follis or Nummus by Roman coin experts. Coins that are not perfectly round are measured at their largest diameter. The AE system generally works well, with the exception of some coins issued in the late 330s, which range in size from large AE4 to small AE3 and are sometimes called AE3/4.