1703 (MDCCIII) was a common year starting on Monday of the Gregorian calendar and a common year starting on Friday of the Julian calendar, the 1703rd year of the Common Era (CE) and Anno Domini (AD) designations, the 703rd year of the 2nd millennium, the 3rd year of the 18th century, and the 4th year of the 1700s decade. As of the start of 1703, the Gregorian calendar was 11 days ahead of the Julian calendar, which remained in localized use until 1923.

In the Swedish calendar it was a common year starting on Thursday, one day ahead of the Julian and ten days behind the Gregorian calendar.