How the start of Ramadan is decided in Malaysia, Singapore and Brunei

What is the difference between rukyah and hisab?

Rukyah is observation. Trained observers watch the western horizon just after sunset on the 29th evening of the outgoing month, looking for the new crescent. Hisab is calculation. It predicts, in advance and to the minute, where the moon will be and how far it will sit from the sun.

The two are not rivals in Malaysian practice. Hisab decides where and when to look, and sets the threshold the sighting is judged against; rukyah confirms it. Malaysia returned to this combined method by a decision of the Conference of Rulers at its 125th meeting on 14 October 1982.

What is the imkanur rukyah criterion?

Imkanur rukyah means the possibility of sighting. Rather than asking whether the crescent has technically been born, it asks whether a crescent could realistically be seen. The criterion sets the numbers that answer that question, and those numbers changed.

The revision was agreed at the 16th Muzakarah on moon sighting and the Islamic calendar, held in Port Dickson from 2 to 4 August 2016, confirmed at the 44th MABIMS Senior Officials Meeting in Singapore from 11 to 14 November 2019, and brought into force from 1443 AH. Malaysia adopted it on 9 August 2021.

This matters more than it looks. A higher threshold means the crescent must be further from the sun before a month may begin, so under the current criterion some months start one day later than they would have under the old one. Several published explanations of Malaysian practice, including pages still online from state mufti departments, continue to quote the superseded 2 and 3 degree figures.

What happens on the 29th of Syaaban?

Every Hijri month runs 29 or 30 days, and which one it is cannot be known until the 29th evening. What follows that evening has two possible outcomes.

1. The criterion is met. The crescent is sighted, or the calculation shows it sitting above the thresholds. The next day is 1 Ramadan.
2. The criterion is not met. Syaaban is completed to a full 30 days, a step called istikmal, and Ramadan begins the day after.

Because a Hijri day turns at sunset rather than at midnight, the month begins that same evening at Maghrib. The first tarawih is prayed that night and the first fast is kept from dawn the following morning.

The same test runs again twenty nine days later, on the 29th of Ramadan, and its answer there decides when Ramadan ends and 1 Syawal begins.

Who decides in each country?

All three apply the MABIMS criterion, but they confirm it differently and announce it through different offices.

Singapore's position is the one most often misread. Photographs of the Mufti at a telescope circulate every year, but Singapore has determined its Hijri months by calculation since 1974. The observation is for data and research, not for deciding when the month starts.

Why do the three countries start on the same day?

They start together because they share the criterion, not because they share the method. Malaysia can sight the crescent while Singapore calculates it, and both arrive at the same date, because both are asking the same question: does the crescent clear 3 degrees of altitude and 6.4 degrees of elongation at sunset.

This is the part that most explanations miss. Method is what a country does on the night. Criterion is what counts as a month beginning. Agreeing on the second is what produces a shared calendar, and MABIMS is the body through which the four member countries agreed it.

Could they ever start on different days?

Yes. A shared criterion narrows the room for disagreement but does not remove it, for three reasons.

• The reference point differs. Each country computes visibility for its own location: Tanjung Chincin for Malaysia, Tuas for Singapore, Bukit Shahbandar for Brunei. On a marginal night, a crescent can clear the threshold at one and fall below it at another.
• The calculation basis differs. Altitude measured from the observer's position on the surface, called topocentric, is not identical to altitude measured from the centre of the earth, called geocentric.
• Jurisprudential reading differs. How a sighting report is weighed, and whether one country's sighting binds another, remains a question of fiqh rather than astronomy.

Why does Indonesia sometimes start a day earlier?

Indonesia is the fourth MABIMS member, and its government's calendar follows the same criterion through a public deliberation called the Sidang Isbat. The divergence is not between Indonesia and its neighbours. It is within Indonesia.

Muhammadiyah, one of the country's largest Islamic organisations, does not use imkanur rukyah. Its calendar has rested on wujudul hilal, the position that a month begins once the crescent exists above the horizon at sunset regardless of whether it could be seen, and it has since moved to a global unified Hijri calendar known as KHGT. Because that threshold is lower, Muhammadiyah can begin a day earlier.

For 1447 AH the two landed on different days: Muhammadiyah set 1 Ramadan on 18 February 2026, and the Indonesian government set it on 19 February 2026, the same day as Malaysia, Singapore and Brunei. Both positions are argued from evidence, and this page reports them rather than choosing between them.

Can the date be known in advance?

Not officially. Calculation can project the date years ahead, and printed calendars do exactly that, which is why a Hijri calendar for 1450 AH already exists. A projection is not an announcement. The date becomes official only after the 29th evening, when the responsible authority in each country declares it.

This is why a date published far in advance should be read as a calculation. It is usually right, because the criterion is arithmetic and the arithmetic is sound. It is not binding until it is announced.

Does this site's countdown use the announced date?

It uses the projection until an authority announces, then the announced date. The countdown runs to Maghrib on the eve, because that is the moment the month begins, and anything still unannounced is labelled as projected rather than confirmed. The next first day of fasting is 8 February 2027.