1850 (MDCCCL) was a common year starting on Tuesday of the Gregorian calendar and a common year starting on Sunday of the Julian calendar, the 1850th year of the Common Era (CE) and Anno Domini (AD) designations, the 850th year of the 2nd millennium, the 50th year of the 19th century, and the 1st year of the 1850s decade. As of the start of 1850, the Gregorian calendar was 12 days ahead of the Julian calendar, which remained in localized use until 1923.