Muhammadiyah’s launch of the Unified Global Hijri Calendar (UGHC) marks a major step in unifying Muslims around the world through a unified, predictable calendar. Introduced at Universitas ‘Aisyiyah Yogyakarta, on June 25, the calendar brings to life a vision that began in the early 20th-century.
Hamim Ilyas, Chairperson of the Muhammadiyah Council for Religious Opinion and Tajdid, said the idea of a unified calendar dates back to 1939 with Egyptian scholar Sheikh Ahmad Muhammad Shakir. In 1978, Professor Mohammad Ilyas of Malaysia proposed a hisab-based calendar divided into three time zones. By 1993, Professor Nidhal Guessoum suggested a four-zone model, later simplified into two zones by Jordanian astronomer Mohammad Odeh. A major breakthrough came in 2004 when Jamaluddin ‘Abd ar-Raziq of Morocco proposed the now-familiar principle: “One day, one date, worldwide.”
“This brilliant concept was formally endorsed by the Organisation of Islamic Cooperation (OIC) in the 2008 Dakar Declaration,” said Hamim. Muhammadiyah officially adopted it in 2024 after discussions at its national conference.
Furthermore, the UGHC is built on three principles, namely global uniformity in determining the start of each lunar month, use of hisab (astronomical calculation) as the basis for time determination, and adoption of a unified lunar time zone (ittiḥād al-maṭāli‘), treating the Earth as one global zone.
Hamim added that the calendar supports Islam’s mission of progress and global unity.
“Muhammadiyah’s adoption of UGHC represents both a theological fulfillment of ad-dīn al-qayyim and a civilizational contribution to global Muslim unity,” said Hamim.
