1764 (MDCCLXIV) was a leap year starting on Sunday of the Gregorian calendar and a leap year starting on Thursday of the Julian calendar, the 1764th year of the Common Era (CE) and Anno Domini (AD) designations, the 764th year of the 2nd millennium, the 64th year of the 18th century, and the 5th year of the 1760s decade. As of the start of 1764, the Gregorian calendar was 11 days ahead of the Julian calendar, which remained in localized use until 1923.