The first day of Ramadan will be April 13, Tuesday. The moon sighting committee in the Kingdom of Saudi Arabia said that the crescent moon had not been sighted. Accordingly, Monday, April 12, will be the last and 30th day of Shaban 1442 Hijri which means, by default, the first day of Ramadan will be on Tuesday.
Sunday marks the 29th day of Shaban, the month before Ramadan according to the Islamic calendar. Ramadan lasts for one complete moon cycle, which is usually 29 or 30 days. The moon sighting determines the duration.