1830 (MDCCCXXX) was a common year starting on Friday of the Gregorian calendar and a common year starting on Wednesday of the Julian calendar, the 1830th year of the Common Era (CE) and Anno Domini (AD) designations, the 830th year of the 2nd millennium, the 30th year of the 19th century, and the 1st year of the 1830s decade. As of the start of 1830, the Gregorian calendar was 12 days ahead of the Julian calendar, which remained in localized use until 1923.