Understanding MABIMS: History, Role, and Latest Crescent Criteria

In the Islamic calendar system in Southeast Asia, the role of MABIMS (Ministers of Religious Affairs of Brunei Darussalam, Indonesia, Malaysia, and Singapore) is highly crucial. This forum serves as a bridge between astronomical science and fiqh law to determine the start of the Hijriah month uniformly in the region. MABIMS was officially established in 1989. This forum is a regional cooperation platform aimed at aligning matters concerning the Muslim ummah. One of its main focuses is unifying the Hijriah calendar so that Muslims in the four member countries can begin and end fasting worship simultaneously or at least within the same criteria framework. Since 2022, Indonesia and other member countries have updated the crescent visibility criteria (Imkanur Rukyat). This change is based on in-depth research on the minimum optical visibility limits of the crescent. These criteria replace the old standard (2 degrees height and 3 degrees elongation), which is considered no longer relevant to modern astronomical data. With higher standards, the potential for observation errors (human error) can be minimised. In 2026, the implementation of these criteria will remain the main reference in the Isbat Session. Nevertheless, differences in the potential determination of the start of the month may still occur if the moon’s position is below the 3-degree threshold but already above the horizon (positive). In such cases, MABIMS prioritises the principle of Ihtiyat (caution) for the validity of worship. To make the criteria more realistic astronomically. Based on global rukyat data, a crescent with a height below 3 degrees is almost impossible to see due to the strong twilight glow (syafaq). MABIMS also collaborates on standardising halal products, empowering the ummah’s economy, and Islamic education in Southeast Asia. With the MABIMS standards, it is hoped that peace will be created for the ummah in performing worship, as every decision is made through thorough scientific consideration and agreement among neighbouring countries. Understand the MABIMS criteria (3 degrees & 6.4 degrees) used by the Ministry of Religious Affairs in the Isbat Session to accurately determine the start of Ramadan and Eid al-Fitr.