Understanding the KHGT Muhammadiyah Hisab Method in Determining Eid al-Adha
Muhammadiyah is undergoing a transformation in the Islamic dating system by adopting the Single Global Hijri Calendar (KHGT). This method serves as the primary basis for determining major Islamic holidays, including Eid al-Adha, using astronomical calculations (hisab) that transcend national borders.
This step is an effort to address the challenges faced by the global Muslim community regarding the frequent discrepancies in the start of Hijri months. With KHGT, Muhammadiyah no longer relies solely on the position of the hilal (crescent moon) in a single local region, but instead uses parameters that are applicable internationally. The KHGT is a calendar system based on the principle of one day, one date, across the entire world, resulting from the decisions made at the International Congress for the Unification of the Hijri Calendar in Istanbul in 2016.
Unlike the previously used Wujudul Hilal method, which focused on whether the hilal was above the horizon within Indonesian territory, KHGT uses broader criteria to ensure global uniformity in dates. In determining Eid al-Adha and other Hijri months, KHGT utilises two main parameters that must be met.
There are several strategic reasons why Muhammadiyah has shifted to this global calculation method:
Predictability: With the KHGT calculation, the date of Eid al-Adha can be known decades in advance. This allows the community to plan the purchase of sacrificial animals with more organised budgeting.
Global Unity: Muhammadiyah views the Hajj pilgrimage and Eid al-Adha as having a global dimension. Through KHGT, it is hoped that there will no longer be significant differences between the performance of the Wuquf at Arafah and the celebration of Eid al-Adha in various parts of the world.
Scientific Advancement: The astronomical calculation method is considered an appreciation of modern science, which is capable of predicting the positions of celestial bodies with extremely high precision.
The Indonesian government, through the Ministry of Religion, currently uses the MABIMS criteria (Ministers of Religious Affairs of Brunei, Indonesia, Malaysia, and Singapore), which requires a hilal height of 3 degrees and an elongation of 6.4 degrees on a local/regional basis. These differing parameters are what occasionally trigger discrepancies in holiday dates in Indonesia, even though both methods are based on scientific principles.
The KHGT Hisab method implemented by Muhammadiyah is not merely a calculation tool, but a vision to unite the Muslim community internationally. With this system, the determination of Eid al-Adha becomes more predictable, scientific, and aligned with the spirit of global unity.
KHGT is used to determine the start of all months in the Hijri calendar, including Ramadan and Eid al-Fitr. Muhammadiyah has not abandoned calculation methods but has upgraded the scale from local (Wujudul Hilal) to global (KHGT) to support the creation of a single international Islamic calendar. KHGT is designed to encompass the entire earth; if the global criteria are met, the date applies internationally, even if visual observations in one country may differ due to weather or geographical factors.