Year 312 (CCCXII) was a leap year starting on Tuesday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Constantinus and Licinianus (or, less frequently, year 1065 Ab urbe condita). The denomination 312 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.

Year 312 (CCCXII) was a leap year starting on Tuesday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Constantinus and Licinianus (or, less frequently, year 1065 Ab urbe condita). The denomination 312 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.