Year 543 (DXLIII) was a common year starting on Thursday of the Julian calendar, the 543rd year of the Common Era (CE) and Anno Domini (AD) designations, the 543rd year of the 1st millennium, the 43rd year of the 6th century, and the 4th year of the 540s decade. As of the start of 543, the Gregorian calendar was 2 days ahead of the Julian calendar, which was the dominant calendar of the time.