Prayer Time Calculation Methods Explained

The Quran fixes prayer to appointed times rather than to clock readings:

Three of those times are tied to something anyone can see. Dhuhr begins once the sun has passed the local meridian — its highest point of the day. Asr begins when shadows have lengthened to a set proportion. Maghrib begins at sunset. The Quran gathers them in a single sweep — “establish prayer from midday until the darkness of the night, and the recitation at dawn” (Sūrat al-Isrāʾ 17:78) — and spherical astronomy pins all three to the minute from your latitude, longitude and the date. Every app on earth agrees about them.

Fajr and Isha are the exceptions. Neither is marked by the sun being anywhere visible. Fajr begins with the first true dawn and Isha once the evening twilight has gone — both of them descriptions of light, not of a position. A prayer time calculation method is simply an agreed way of turning that light into a number: how far below the horizon the sun's centre must be for dawn to be considered broken, or for twilight to be considered finished.

Because the scholars who set these methods were describing the same phenomenon from different places, with different horizons and different judgements about when faint light counts as dawn. The reference point in the Sunnah is observational. In the well-known narration of Ibn ʿAbbās, Jibrīl led the Prophet ﷺ in prayer across two days to mark the boundaries, praying Isha “when the twilight had vanished” and Fajr “when dawn began, and when eating is prohibited for the fasting person” (Jāmiʿ al-Tirmidhī 149).

The Quran draws the same line for the fasting person, and draws it by sight:

A white thread against a black one is a perfectly clear instruction in the desert and a genuinely hard one to automate. How bright is distinct? Observers in Makkah, Cairo and Karachi answered slightly differently, and those answers hardened into the angles we now choose between in a settings screen. Three degrees of disagreement sounds trivial; at a British latitude in late summer it is twenty-five minutes of your morning.

Five methods cover the overwhelming majority of mosques worldwide. The number is the angle of the sun's centre below the horizon — larger means the sun is deeper down, so an earlier Fajr and a later Isha.

Two things in that table are worth pausing on. ISNA's 15° is the shallowest in common use, which makes its Fajr noticeably later and its Isha noticeably earlier than the others — a deliberate accommodation of North American latitudes, where deeper angles push Isha past midnight for much of the year.

Umm al-Qura is the odd one out entirely: it does not use an Isha angle at all, but a fixed interval of ninety minutes after Maghrib, stretching to a hundred and twenty during Ramadan. That is why switching to it can move your Isha by a great deal more than a couple of degrees ever would.

The honest answer is the one your community prays by. Prayer times are not a private calculation — they are the schedule of the congregation, and the reward of praying with the jamāʿah outweighs a few minutes of theoretical precision. So the order of preference is simple:

• Match your local mosque first. Check the timetable on the wall or their website, then try methods until the Fajr and Isha columns line up. That is the whole exercise.
• If you cannot ask, use the regional convention. MWL across Europe and much of the world, ISNA in North America, Umm al-Qura in Saudi Arabia, Karachi across the Indian subcontinent, and the Egyptian method across much of North Africa and the Levant.
• When two mosques nearby disagree, follow the one you actually pray at, and keep that setting through the year rather than drifting between methods by season.
• Fine-tune with an offset, not a new method. Once you are within a few minutes, a manual adjustment on Fajr or Isha is the cleanest way to match the board exactly.

It is a separate setting, and conflating the two is the most common source of confusion. Asr is not governed by twilight at all, but by shadow length — and the two readings of it come from fiqh rather than from astronomy.

ʿAbdullāh ibn ʿAmr reported the Prophet ﷺ describing the noon prayer as beginning when the sun passes the meridian and a man's shadow equals his own height (Sahih Muslim 612a). From that family of narrations, two positions follow:

• Standard — the Shāfiʿī, Mālikī and Ḥanbalī view: Asr begins when an object's shadow equals its own length, added to whatever shadow it cast at midday.
• Ḥanafī — Asr begins when that shadow reaches twice the object's length, again added to the midday shadow. In practice this falls roughly thirty to sixty minutes later, depending on season and latitude.

Both are long-established positions held by recognised schools, and the question of which to follow belongs to your own madhhab and your local scholars rather than to an app's settings screen. What an app owes you is the ability to express the one you follow — which is why the madhhab option sits beside the calculation method rather than inside it.

Above roughly 48° of latitude — Paris and north, most of Britain, the Low Countries, Germany, Scandinavia, Canada's prairies — something breaks in midsummer. The sun sets, but it never descends 18° below the horizon before beginning to climb again. Twilight simply never ends. The angle a method asks for is never reached, so there is no astronomical Fajr and no astronomical Isha to calculate.

Apps handle this with a high-latitude rule, which estimates the missing times from the length of the night instead:

• Middle of the night — the night between sunset and sunrise is halved; Isha ends and Fajr begins at that midpoint.
• One-seventh of the night — Isha begins after the first seventh of the night has passed, and Fajr a seventh before sunrise.
• Angle-based — the night is divided in proportion to the method's own Fajr and Isha angles, so the estimate stays closer to what the method would have given.

None of these is a calculation in the strict sense; each is a considered approximation, and mosques in the same northern city sometimes adopt different ones. If you live at a high latitude, this setting matters more than your choice of method — and it is worth asking your local imam which rule the community follows.

Itabah is a free Islamic app for iPhone and Android, and it treats the calculation method as yours to set rather than something to guess at on your behalf. Open Profile → Prayer settings and you can choose:

• The calculation method — Muslim World League, ISNA, Umm al-Qura, the Egyptian General Authority of Survey, University of Islamic Sciences Karachi, and others.
• The madhhab for Asr — Ḥanafī, or the standard Shāfiʿī reading.
• A high-latitude rule, for northern locations where twilight does not end in summer.
• A per-prayer offset in minutes, to match your mosque's timetable exactly.

Everything is computed on your device from your GPS position. Your location is used to work out the times and the Qibla and then stays on your phone — it is never uploaded, never sold, and no account is needed to use any of it. You can watch the same astronomy run in your browser on the live prayer-times arc on the home page, which uses the identical calculation the app does.

If you are still finding your footing with the prayers themselves, our step-by-step guide to praying salah walks through each rakʿah, and the free rituals guide inside Itabah covers wuḍūʾ, ghusl and tayammum with every recitation in Arabic, transliteration and meaning.