BMKG and BRIN Predict Eid al-Fitr 2026 to Fall on 21 March: Here is the Scientific Reasoning!

The Indonesian Agency for Meteorology, Climatology, and Geophysics (BMKG) and the National Research and Innovation Agency (BRIN) have released a prediction regarding the determination of Eid al-Fitr 1447 Hijriah, or Lebaran 2026. Based on astronomical data, 1 Syawal 1447 H is highly likely to fall on Saturday, 21 March 2026.

BRIN Senior Researcher Thomas Djamaluddin stated that the moon’s position on Thursday, 19 March 2026, at sunset does not meet the visibility criteria for the hilal (new moon crescent) agreed upon by MABIMS countries.

According to the BMKG’s hilal forecast report, at Maghrib on 19 March 2026, the hilal’s height in Indonesian regions remains very low. In Merauke, Papua, the hilal height is recorded at only 0.91 degrees, while the highest position in Sabang, Aceh, reaches 3.13 degrees.

However, another key parameter, elongation (the angular distance between the moon and the sun), is observed to be only in the range of 4.54 to 6.1 degrees. This figure is still below the minimum MABIMS criterion, which sets a minimum elongation of 6.4 degrees.

This situation opens the possibility of differing Eid al-Fitr celebration dates in Indonesia. Muhammadiyah, through its Global Unified Hijriah Calendar (KHGT), has set 1 Syawal 1447 H on Friday, 20 March 2026.

This difference arises from the use of different criteria. Muhammadiyah employs a calculation method that does not require physical visibility of the hilal in Indonesian territory, as long as global conditions are met.

BMKG also reminds field observers to be cautious of other astronomical objects, such as bright planets near the hilal, which could lead to misidentification.

The government’s final decision will be determined at the Isbat Session held by the Ministry of Religious Affairs on 19 March 2026, after collecting reports on hilal sighting results from various points across Indonesia.