1608 (MDCVIII) was a leap year starting on Tuesday of the Gregorian calendar and a leap year starting on Friday of the Julian calendar, the 1608th year of the Common Era (CE) and Anno Domini (AD) designations, the 608th year of the 2nd millennium, the 8th year of the 17th century, and the 9th year of the 1600s decade. As of the start of 1608, the Gregorian calendar was 10 days ahead of the Julian calendar, which remained in localized use until 1923.