01 / Birth
The new moon
The conjunction, when the moon passes between the earth and the sun. The crescent cannot be seen before it, and rarely within 15 hours after.
Moon sighting, will the crescent be seen tonight?
Pick your city and the month. See when the new moon is born, how old and how high the moon is at sunset on the 29th, how long it stays up after the sun, and how easy it is to see.
Crescent visibilityPick a place to see the moon
We work out the sun and moon for your place on the evening of the 29th and the evening after.
| At sunset | 29th | 30th |
|---|---|---|
| Choose a place. | ||
The same evening around the world
| City | Moon age | Lag | Estimate |
|---|
- Next new moon
- …
- Moon age now
- …
- Lit now
- …
- Umm al-Qura start
- …
- Saudi rule at Makkah
- …
Your location stays in your browser. Astronomy by astronomy-engine (MIT licence). A calculation is an estimate: clouds, haze and the sighter's eyes decide what is actually seen.
How it works
Three numbers, one estimate.
02 / Sunset
Age, altitude and lag
At sunset on the 29th we measure how old the moon is, how high it sits, how far it is from the sun and how long it stays up.
03 / Estimate
Yallop's q test
Those numbers go into Yallop's criterion, used by HM Nautical Almanac Office, which gives one of six visibility classes.
Guide
Moon sighting, the calculation and the two views.
Each Islamic month begins when the new crescent (hilal) is seen after sunset on the 29th day. If it is not seen, the month is completed as 30 days. The calculator above shows whether the crescent can be seen from your city on that evening, from the positions of the sun and moon. For Ramadan 2027, the new moon is born on 6 February 2027 at about 15:56 GMT, and the crescent is expected to be visible in parts of the world on the evening of 7 February.
يَسْـَٔلُونَكَ عَنِ ٱلْأَهِلَّةِ ۖ قُلْ هِىَ مَوَٰقِيتُ لِلنَّاسِ وَٱلْحَجِّ ۗ وَلَيْسَ ٱلْبِرُّ بِأَن تَأْتُوا۟ ٱلْبُيُوتَ مِن ظُهُورِهَا وَلَٰكِنَّ ٱلْبِرَّ مَنِ ٱتَّقَىٰ ۗ وَأْتُوا۟ ٱلْبُيُوتَ مِنْ أَبْوَٰبِهَا ۚ وَٱتَّقُوا۟ ٱللَّهَ لَعَلَّكُمْ تُفْلِحُونَ
Yas'aloonaka 'anil ahillati qul hiya mawaaqeetu linnaasi wal Hajj; wa laisal birru bi an taatul buyoota min zuhoorihaa wa laakinnal birra manit taqaa; waatul buyoota min abwaa bihaa; wattaqullaaha la'allakum tuflihoon
"They ask you, [O Muhammad], about the new moons. Say, "They are measurements of time for the people and for Hajj." And it is not righteousness to enter houses from the back, but righteousness is [in] one who fears Allah. And enter houses from their doors. And fear Allah that you may succeed."
Quran 2:189, translation by Sahih International.
The Prophet ﷺ said: "Fast when you see it and break your fast when you see it. If it is hidden from you, complete Shaban as thirty days."1
What the numbers mean
- New moon (conjunction): the moment the moon is in line with the sun. It is invisible then. The crescent appears once it has moved far enough from the sun.
- Moon age: the time from the conjunction to sunset. Under 15 hours, the crescent is almost never seen by eye. Over 24 hours it is often seen if the sky is clear.
- Moonset minus sunset (lag): how long the moon stays above the horizon after the sun. If the moon sets first, it cannot be seen. A lag of 40 minutes or more helps.
- Altitude: how high the moon is at sunset. A low moon is lost in haze.
- Elongation: the angle between the moon and the sun. Below about 7 degrees (the Danjon limit) there is no visible crescent at all.
The visibility estimate
We use the q test of B. D. Yallop (HM Nautical Almanac Office, 1997), worked out at the "best time", a little after sunset. It compares the moon's height above the sun with the width of the crescent and gives six classes: A, easily visible to the eye; B, visible in perfect conditions; C, may need binoculars to find it first; D, needs binoculars or a telescope; E, not visible even with a telescope; F, not visible at all. It is a guide only. Weather and experience decide what is really seen.
Global or local sighting?
Hanafi position
In the main transmitted position of the school (zahir al-riwayah), differences in the horizon (ikhtilaf al-matali) are not taken into account: a sighting established in one place binds others when it reaches them through a reliable route. Many later Hanafi scholars, including al-Zaylai, said distant lands may each follow their own sighting. On a clear sky, the Ramadan and Eid crescents are accepted only from a large group of witnesses; when it is cloudy, one reliable witness is enough for Ramadan and two for Eid.2
Other madhhabs
- Shafi'i
- Each region follows its own sighting, because horizons differ. This rests on the report of Kurayb, when Ibn Abbas in Madinah did not follow the sighting in Syria (Sahih Muslim 1087).
- Maliki, Hanbali
- A sighting anywhere binds all Muslims who learn of it, like the main Hanafi position.
Today this produces three common practices. Some communities follow Saudi Arabia or another country's announcement. Some follow a sighting anywhere in their region or continent. Some follow only their own local sighting. Each has scholarly support, and families do best by following their local masjid or council so the community fasts and celebrates together.
Can calculation replace sighting?
The four schools held that the month is established by sighting, or by completing 30 days, not by calculation alone. Many contemporary scholars accept calculation to reject a claimed sighting that is astronomically impossible, such as one reported when the moon had already set. Some councils, including the Fiqh Council of North America and Turkey's Diyanet, start the months by calculation. Saudi Arabia's Umm al-Qura calendar starts a month when, on the 29th at Makkah, the new moon is born before sunset and the moon sets after the sun; the official Ramadan and Eid dates are still announced after a sighting.
When you see the crescent
اللَّهُمَّ أَهْلِلْهُ عَلَيْنَا بِالْيُمْنِ وَالإِيمَانِ، وَالسَّلَامَةِ وَالإِسْلَامِ، رَبِّي وَرَبُّكَ اللَّهُ
Allāhumma ahlilhu ʿalaynā bil-yumni wal-īmān, was-salāmati wal-islām, rabbī wa rabbukallāh
"O Allah, bring it over us with blessing and faith, with safety and Islam. My Lord and your Lord is Allah."
Jami at-Tirmidhi 3451, from Talhah ibn Ubaydullah, graded hasan. Said on seeing the new crescent of any month.
- Sahih al-Bukhari 1909; Sahih Muslim 1081.
- Al-Marghinani, al-Hidayah, Kitab al-Sawm, on sighting the crescent; Ibn Abidin, Radd al-Muhtar; al-Zaylai, Tabyin al-Haqa'iq. The other madhhabs' positions are summarised from their standard manuals.
- B. D. Yallop, A Method for Predicting the First Sighting of the New Crescent Moon, NAO Technical Note 69 (1997).
- Sun and moon positions: astronomy-engine by Don Cross (MIT licence).
The rulings on this page are pending review by the scholars on our team.
Questions
Good to know.
When is the moon sighting for Ramadan 2027?
On the evening of 29 Shaban 1448, which is Saturday 6 February 2027 by the Umm al-Qura calendar. The new moon is born that day at about 15:56 GMT, so the crescent cannot be seen that evening and Ramadan is expected to begin on Monday 8 February 2027.
When is the moon sighting for Eid al-Fitr 2027?
On the evening of 29 Ramadan, Monday 8 March 2027. If the crescent is seen, Eid al-Fitr is on Tuesday 9 March 2027. If not, Ramadan completes 30 days and Eid is the day after.
How old must the moon be to be seen?
There is no single age. As a rough guide, the crescent is very rarely seen by eye under 15 hours old and often seen after 24 hours, if it is high enough and far enough from the sun. The calculator uses Yallop's q test instead of age alone.
Can I see the new moon on the day of the conjunction?
Almost never. At the conjunction the moon is in line with the sun and its lit side faces away from us. The thin crescent appears on the next evening or the one after.
Why do countries start Ramadan on different days?
Some follow Saudi Arabia, some follow a sighting in their own region, and some calculate. When the crescent is on the edge of visibility, this splits countries across two days.