1672 (MDCLXXII) was a leap year starting on Friday of the Gregorian calendar and a leap year starting on Monday of the Julian calendar, the 1672nd year of the Common Era (CE) and Anno Domini (AD) designations, the 672nd year of the 2nd millennium, the 72nd year of the 17th century, and the 3rd year of the 1670s decade. As of the start of 1672, the Gregorian calendar was 10 days ahead of the Julian calendar, which remained in localized use until 1923.