Saudi Arabia announced that Eid al-Fitr will begin on Friday, March 20, after the crescent moon marking the end of Ramadan was not sighted.
Saudi religious authorities said the moon was not visible during observations on Wednesday evening, meaning the holy month of Ramadan will complete 30 days this year.
Several other countries in the region also confirmed that Eid will fall on Friday.
Eid al-Fitr marks the end of Ramadan, the Islamic holy month of fasting, and is celebrated by Muslims worldwide.
The holiday typically begins with morning prayers, drawing large gatherings of worshippers, followed by meals shared with family and friends.
In Saudi Arabia, families traditionally serve sweets, dates and Arabic coffee, along with dishes such as kabsa, jareesh and other local specialties.
Across the Muslim world, celebrations vary by country, but commonly include communal meals, charitable giving and visits with relatives.