Why your prayer times don't match your mosque

You open a prayer app, and it says Fajr is at 5:15. The timetable on the wall at your masjid says 4:56. Neither is broken, and the nineteen minutes between them are not a rounding error.

They are a decision somebody made about what the sky has to look like before Fajr begins.

#Six answers for the same morning

Here is the same city on the same day, calculated six ways. London, 29 October 2026, standard Asr, run through the Aladhan API:

Twenty-nine minutes between the earliest and latest Fajr. Twenty-seven between the Isha times. One city, one morning, one sun.

So when your app and your mosque disagree, the first question is not "which one is wrong" but "which convention is each of them using".

#Fajr and Isha are an angle, not a time

Dhuhr, Asr and Maghrib are tied to things you can see: the sun crossing its highest point, a shadow reaching a certain length, the sun setting.

Fajr and Isha are tied to twilight — the glow before sunrise and after sunset. And twilight does not end at a moment you can point at. It fades.

So the convention is to define it by how far the sun has sunk below the horizon. Fajr begins when the sun is a certain number of degrees below; Isha begins when it has sunk that far on the other side.

Different authorities chose different numbers:

• ISNA — 15° for both Fajr and Isha
• Muslim World League — 18° for Fajr, 17° for Isha
• University of Islamic Sciences, Karachi — 18° and 18°
• Umm al-Qura, Makkah — 18.5° for Fajr; Isha is not an angle at all but 90 minutes after Maghrib, extended to 120 during Ramadan
• Egyptian General Authority — 19.5° and 17.5°

A smaller angle means the sun has less distance to travel, so ISNA's 15° produces a later Fajr and an earlier Isha than the 18° methods. That is the whole of it. Nothing is being calculated wrongly; the apps are answering slightly different questions.

Two more things follow from this.

The gap changes through the year. The sun descends at a steeper angle in some seasons than others, so the distance between two methods is not a fixed number of minutes you can memorise.

Your latitude changes it too. The further from the equator, the more slowly the sun crosses those degrees, and the wider the spread between methods becomes. This is why the disagreement feels much worse in Britain than in Karachi.

#Asr is a separate setting

This one surprises people, because they go looking in the calculation method and it is not there.

Asr is not a twilight question. It is a shadow question, and the two main positions are:

• The majority view (Shafi'i, Maliki, Hanbali, Ja'fari): Asr begins when an object's shadow equals the object's own height, plus whatever shadow it cast at noon.
• The Hanafi view: Asr begins when the shadow reaches twice the object's height, plus its noon shadow.

Waiting for a second object-length of shadow takes real time. In the London table above, Asr was 14:12 on the standard view and 14:50 on the Hanafi one — thirty-eight minutes — and that gap was identical under every calculation method I tried, because the method has nothing to do with it.

So if your Fajr matches your mosque and your Asr is wildly out, you have the right method and the wrong madhab setting. They are two separate switches and both have to be right.

#When the angle never arrives

Now the problem that Muslims in Britain, Ireland, Canada, Scandinavia and the northern United States know well.

If Fajr is defined as the sun being 18° below the horizon, what happens in a place where, in June, the sun never gets 18° below the horizon at all?

The calculation returns nothing. There is no such moment.

Something has to fill the gap, and the conventions are these:

• Middle of the night — the span from sunset to sunrise is halved, and Fajr and Isha are placed at that midpoint during the abnormal period.
• One-seventh of the night — the night is divided into seven parts; Isha starts after the first seventh, Fajr at the start of the last.
• Angle-based — an intermediate approach that splits the night in proportion to the twilight angle the method uses.

These produce visibly different answers, which is why in a British summer two apps can be an hour apart on Isha while agreeing precisely on Dhuhr.

Your mosque has chosen one of these rules, usually with scholars involved, and often prints the result rather than the rule. If your app offers a high-latitude setting, that is the switch to match.

#How to match your mosque

Four steps, in this order, in whichever app you use.

1. Find out what your mosque uses. Many printed timetables name the method in small type at the bottom. If not, ask — the committee will know, and it is a reasonable thing to ask.

2. Set the calculation method. This fixes Fajr and Isha. If you are now within a few minutes on those two, you have the right one.

3. Set the Asr madhab. Standard or Hanafi. This one is yours to follow rather than the app's to guess, and it will not be right by accident.

4. Add a minute offset for anything still out. Mosques routinely add a few minutes of safety margin to the calculated time, especially for Fajr. A good app lets you nudge individual prayers by a minute or two. That is not fudging the numbers — it is matching the jamaat you actually pray with.

If after all four you are still far apart on Fajr and Isha in summer, go back and check the high-latitude rule.

#A note on the app I build

Disclosed interest: Qurbah is mine.

It carries the methods named above — ISNA, Muslim World League, Moonsighting Committee, Umm al-Qura, the Egyptian authority, Diyanet, Karachi, Kuwait, Qatar, Dubai and Singapore — with Asr as a separate Hanafi or standard choice, a high-latitude rule you can select, twilight angles you can set by hand in half-degree steps, and a minute offset per prayer. Those four settings are there precisely because of everything above.

The times are computed on the device, so it works with no connection, and you can skip location entirely and choose your city by hand. There are no ads, no sign-up and no analytics — in a category where prayer apps have been reported selling location data to brokers, that felt like the least it could do. It is free on iPhone and Android, and the Qur'an inside it carries Saheeh International, Yusuf Ali and Pickthall alongside four Urdu translations.

If you take one thing from this page, make it the second and third steps: method, then madhab. Most mismatches die right there.

#Frequently asked questions