Representatives from around 50 countries including Turkey, Malaysia, Egypt and the U.S. agreed the proposal at a conference in Istanbul.
“The congress has chosen the single calendar to practice across the whole world,” Mehmet Gormez, the head of Turkey’s Religious Affairs Directorate, said at the meeting.
He said the Hijri calendar would be presented to the Organization of Islamic Cooperation for implementation among member countries.
The Hijri is a lunar calendar used to determine religious occasions such as Ramadan and the Hajj pilgrimage. However, different interpretations of the Quran have led Muslims around the world to celebrate on differing days.
The two-day congress brought together astronomers and officials to create a unified calendar.