Holidays and observances
How the Start of Ramadan Is Decided Each Year
Ramadan begins if the crescent is seen on the evening of 29 Sha'ban; if not, Sha'ban runs to 30 days. How sighting, calculation and announcements work.
By Tahir Nasuru · · 7 min read
The start of Ramadan is decided on the evening of 29 Sha'ban, the month before it. If the new crescent (the hilal) is seen after sunset that evening, Ramadan begins that night and the first fast is the next day. If it is not seen, Sha'ban is completed to 30 days and Ramadan begins one evening later. Communities differ on whose sighting counts and whether calculation can be used, so the final word comes from the authority each community follows, usually announced on the night itself.
Key Takeaways
- There are only two possible outcomes on 29 Sha'ban: Ramadan starts after that sunset, or one sunset later after Sha'ban completes 30 days.
- The hadith tie the start of the fast to seeing the crescent, and to completing 30 days of Sha'ban when it cannot be seen.
- Some authorities rely on local sighting, some accept sighting from other regions, and some use astronomical calculation set in advance.
- A calculated calendar gives a reliable planning date, but the date you observe may differ, usually by a day and occasionally more.
The rule in the hadith
The basic rule comes from the Prophet ﷺ. In Sahih al-Bukhari 1906, he said not to fast until the crescent is seen and not to stop fasting until it is seen, and to estimate the month if the sky is overcast. The narration in Sahih al-Bukhari 1909 explains that estimate: if the sky is overcast, complete thirty days of Sha'ban.
That is why an Islamic month always has 29 or 30 days, never 28 or 31. On the 29th, either the new month's crescent is seen or the current month runs one more day. The reasons a month cannot be longer or shorter are covered in why an Islamic month has 29 or 30 days.
The hadith also show that one person's sighting could be acted on. In Sunan Abi Dawud 2342, graded sahih by al-Albani on sunnah.com, Abdullah ibn Umar reports that people looked for the crescent, he told the Prophet ﷺ that he had seen it, and the Prophet ﷺ fasted and told the people to fast. How many witnesses are needed, and what makes a report acceptable, are questions the schools of law answer in detail.
What happens on the evening of 29 Sha'ban
The process runs on one evening and looks much the same wherever sighting is used.
- The 29th is fixed. The authority first establishes which day is 29 Sha'ban, based on when Sha'ban itself began.
- People look west after sunset. The crescent, if present, is a thin arc low over the western horizon shortly after sunset, and it sets soon after the Sun.
- Reports are made and checked. Anyone who sees it reports to the body that receives testimony, which then decides whether to accept it.
- An announcement is made. The decision is usually published later that same evening.
The outcome is one of two:
| What happens on the evening of 29 Sha'ban | First night of Ramadan | First fast |
|---|---|---|
| The crescent is seen and the report is accepted | That same night | The next day |
| The crescent is not seen | The following night | The day after next |
Because the Islamic day begins at sunset, "Ramadan begins" means the evening, not the morning. The first suhoor comes before dawn on the first fasting day.
An example of an official call to sight the crescent
Saudi Arabia shows how this works in practice. In February 2026, the Supreme Court asked Muslims in the Kingdom to look for the Ramadan crescent on the evening of Tuesday, 29 Sha'ban 1447. As reported by Arab News from the Saudi Press Agency, it asked anyone who saw it, "whether with the naked eye or using binoculars," to register their testimony at the nearest court. The same report set out both outcomes: Ramadan on Wednesday if the crescent was sighted, or on Thursday with 30 days in Sha'ban if it was not.
Who decides, and why answers differ
The method above leaves one large question open: whose sighting counts? Muslims have long differed on this, and the main positions are held by qualified scholars and institutions.
- Local sighting. Each region relies on a sighting within its own area or horizon. A crescent seen far away does not start the month locally.
- Wider or global sighting. A reliable sighting in one place is accepted for a wider region or for everyone, often following an announcement from another country.
- Astronomical calculation. The start of the month is set in advance by a published criterion. The Fiqh Council of North America's 2026 announcement states that it "recognizes astronomical calculation as an acceptable Shar'i method" for the start of lunar months, using a criterion that, somewhere on the globe at sunset, the Moon is at least 8 degrees from the Sun and 5 degrees above the horizon. On that basis it gave Wednesday, 18 February 2026 as the first day of Ramadan 1447.
A well-known early example of regions starting on different days is the narration of Kurayb in Sahih Muslim 1087. He reported that in Syria the crescent was seen on the night of Friday and people fasted, while in Madinah it had been seen on Saturday night. Ibn Abbas kept to the Madinah sighting and said that this is how the Messenger of Allah ﷺ had commanded them. Scholars draw different conclusions from it, which are laid out in global vs local moon sighting. For the wider debate on sighting and calculation, see moon sighting vs calculation.
Which approach to follow is a religious decision. It belongs with your local mosque and the scholars you trust, not with a calendar app.
Why a calculated calendar is only a planning date
Calendars printed months ahead cannot wait for 29 Sha'ban. They use a rule instead. This site follows the Umm al-Qura calendar of Saudi Arabia, which R.H. van Gent of Utrecht University describes as used by the Saudi government for civil purposes. Under its current rule, a month begins after the 29th if, at Makkah that evening, the new moon (conjunction) happens before sunset and the Moon sets after the Sun. Otherwise the month runs to 30 days.
That rule does not require the crescent to be visible. The US Naval Observatory's crescent visibility page explains that the new moon can be computed exactly, but whether the crescent is seen "cannot be predicted with certainty": it depends on sky conditions and the observer's location, experience and preparation. The youngest reliable reports it cites are about 15.5 hours after new moon by naked eye and 12.1 hours with a telescope. So a calculated start and a sighted start often agree, but not always.
Van Gent's introduction to the Umm al-Qura calendar notes that differences between calendars are most noticeable around Ramadan and Dhu al-Hijjah, and that observed festival dates can differ by one, two or even three days. The two events in this process, the new moon and the first visible crescent, are explained in new moon vs first crescent.
Worked example: Ramadan 1448 (February 2027)
The figures below come from the calculated Umm al-Qura calendar and USNO data for Makkah (UTC+3).
- Saturday 6 February 2027 is 29 Sha'ban 1448. USNO's moon phase data puts the new moon at 15:56 UT, which is 18:56 in Makkah. The USNO Sun and Moon data service gives sunset at 18:13 and moonset at 18:07. The new moon comes after sunset and the Moon sets before the Sun, so there is no crescent to see in Makkah that evening and the Umm al-Qura rule gives Sha'ban 30 days.
- Sunday 7 February is 30 Sha'ban. At sunset (18:14) the Moon is about 23 hours old and sets at 18:59, 45 minutes after the Sun. Ramadan begins that evening.
- Monday 8 February is 1 Ramadan 1448, the first fast in the calculated calendar.
The International Astronomical Center's Ramadan 1448 page gives the same new-moon time and lists Monday 8 February as the first day in its own calculated calendar, while noting that a country or organization "might adopt different criterion." For a community whose 29 Sha'ban falls on Saturday, the outcome is effectively known in advance. Even at sunset in Los Angeles, about ten hours after Makkah's, USNO data put the Moon at only about 9.5 hours old, younger than the 12.1-hour telescopic record that USNO cites. So a sighting that evening is not expected, Sha'ban is completed, and Monday is the first fast. A community that began Sha'ban a day later will hold its 29th on Sunday evening instead, and a sighting then decides between Monday and Tuesday.
The rest of the month in the calculated calendar can be seen in the Ramadan 1448 calendar.
How to plan for the start of Ramadan
- Plan around the calculated date. Treat 1 Ramadan as Monday 8 February 2027 for leave requests, meal plans and travel, with Tuesday 9 February possible for communities whose 29 Sha'ban falls on Sunday.
- Find out who you follow. Ask your mosque which authority or method it uses, and where it announces on the evening of 29 Sha'ban.
- Write the evening into plans. "Ramadan begins Sunday evening, first fast Monday" is clearer than a date alone.
- Wait for the announcement on the night. Confirm before telling family the first fast is tomorrow.
To watch the days count down, open the Ramadan countdown, which uses the calculated date and notes that local announcements may differ by a day. To check any other date, use the date converter.
