1730 (MDCCXXX) was a common year starting on Sunday of the Gregorian calendar and a common year starting on Thursday of the Julian calendar, the 1730th year of the Common Era (CE) and Anno Domini (AD) designations, the 730th year of the 2nd millennium, the 30th year of the 18th century, and the 1st year of the 1730s decade. As of the start of 1730, the Gregorian calendar was 11 days ahead of the Julian calendar, which remained in localized use until 1923.