Why Prayer Times Differ Between Apps, Mosques and Calendars

You open two prayer apps and Fajr is 14 minutes apart. The calendar on the mosque wall shows a third time. Before assuming something is broken, it helps to know that most of these differences are deliberate. Prayer times are calculated from the position of the sun, but the exact definitions behind each prayer vary between scholarly bodies, countries and even individual mosques.

Here is what actually causes the gaps, and how to decide which times to follow.

Fajr and Isha depend on a twilight angle

Dhuhr and Maghrib are relatively easy to agree on: Dhuhr begins just after the sun passes its highest point, and Maghrib begins at sunset. Fajr and Isha are different. They are tied to twilight, the light in the sky while the sun is below the horizon, and twilight fades gradually rather than switching off at a clear moment.

To turn "the appearance of true dawn" or "the disappearance of twilight" into a number, calculation methods use the sun's depression angle: how many degrees the sun sits below the horizon. Fajr begins when the sun rises to a certain angle below the horizon before sunrise; Isha begins when it sinks to a certain angle after sunset. Organizations reached different conclusions from observation and juristic reasoning, so they use different angles:

A larger angle means an earlier Fajr and a later Isha. Near the equator, the sun moves through one degree of depression in roughly four minutes, so the three-degree gap between ISNA and the Muslim World League shifts Fajr by about 12 minutes. Farther from the equator the sun descends at a shallower slant, each degree takes longer, and the same gap can grow to half an hour or more in summer.

Note that Umm al-Qura does not use an angle for Isha at all. It sets Isha at a fixed interval after Maghrib, so its Isha time can differ noticeably from angle-based methods, and the gap changes with the seasons.

Asr: one shadow length or two

Asr is defined by the length of shadows in the afternoon, and here there is a well-known difference among the schools of law:

• Shafi'i, Maliki and Hanbali (the majority view): Asr begins when an object's shadow equals its own length, plus the length of the shadow it had at noon.
• Hanafi: Asr begins when the shadow equals twice the object's length, plus the noon shadow.

Both views have a long scholarly history. The practical effect is that the Hanafi Asr time comes later, often by 30 minutes to over an hour depending on the season and latitude. If your family follows the Hanafi school, as is common in Türkiye, South Asia and Central Asia, an app set to the majority rule will show Asr much earlier than your mosque, and vice versa.

Safety minutes: temkin and ihtiyat

Some authorities do not publish the raw astronomical moment. They add or subtract a few minutes as a precaution, called temkin in Turkish and ihtiyat in Arabic and Indonesian. The reasons include:

• A city covers a large area, and a single timetable has to be valid for its eastern and western edges.
• Elevation, refraction near the horizon and small rounding differences can move the true moment slightly.
• It is safer to start a prayer slightly after its time has begun than slightly before, and to stop eating for the fast slightly early.

Türkiye's Diyanet is a clear example. On top of its 18° and 17° angles, its calculation moves sunrise 7 minutes earlier and shifts Dhuhr by 5 minutes, Asr by 4 minutes and Maghrib by 7 minutes later. Indonesia's Kemenag adds a couple of minutes of ihtiyat to each time. An app that uses the same angles but skips these adjustments will still disagree with the official calendar by several minutes.

High latitudes: when twilight never ends

Above roughly 48.5° latitude, the sun does not sink 18° below the horizon around the summer solstice. That includes cities such as Paris, London, Berlin and Stockholm. On those nights, a strict angle-based Fajr or Isha simply does not exist, so methods fall back on a rule, for example:

• Middle of the night: Isha and Fajr cannot be later or earlier than the midpoint between sunset and sunrise.
• One-seventh of the night: the night is divided into seven parts; Isha begins no later than after the first seventh, Fajr no earlier than the start of the last seventh.
• Twilight angle based: the night is divided in proportion to the angle (for 18°, 18/60 of the night).

Each rule produces different summer times, which is why mosques in northern Europe often publish their own timetable and why two apps can disagree by an hour or more in June.

Mosque times are often iqamah times

Many mosque calendars list two columns: the adhan (when the prayer time begins) and the iqamah (when the congregation actually stands to pray). The iqamah may be 10 to 20 minutes after the start, or fixed at a round time such as 1:30 pm for Dhuhr all year. An app shows when the time begins, not when your mosque prays together. Neither is wrong; they answer different questions.

Location and time zone

A calculation is only as good as the coordinates and clock it uses.

• Coordinates: Moving one degree of longitude east makes solar times about four minutes earlier. A printed city calendar is computed for one reference point, so if you live far from it, your times can differ from it slightly. If an app uses a city center or an outdated location, the same applies.
• Time zone and daylight saving time: If the device's time zone is wrong, or a calendar was printed before a daylight saving change, every time can be off by exactly one hour.
• Travel: After a trip, an app that has not updated your location will show times for where you were, not where you are.

When every prayer is off by the same number of minutes, suspect location or time zone. When only Fajr and Isha are off, suspect the angle. When only Asr is off, suspect the madhab setting.

How to choose the right times

1. Follow your local authority or mosque. In Türkiye that usually means Diyanet; in Indonesia, Kemenag; in Egypt, the Egyptian method; in Saudi Arabia, Umm al-Qura. In other countries, ask your mosque which method and which high-latitude rule its timetable uses.
2. Match the Asr setting to your school. Choose Hanafi or the majority view deliberately rather than leaving the default.
3. Compare against one trusted timetable. Pick a single day, compare all six times, and adjust until they line up. Remaining differences of a minute or two usually come from rounding.
4. Check location and time zone after travel and daylight saving changes.

WAQT, for example, suggests a starting method based on your country and lets you choose among 25 calculation methods, including Diyanet, Kemenag, Umm al-Qura, ISNA and a custom option where you set the angles and high-latitude rule yourself. You can also switch Asr between Hanafi and the majority view, and shift each prayer time individually by up to 30 minutes in either direction, so it can match your mosque's calendar exactly.

In short

Different prayer times rarely mean one source is wrong. They usually reflect a different twilight angle, a different Asr opinion, added safety minutes, a high-latitude rule, or simply a different location. Choose the method your local community follows, set Asr according to your school, fine-tune against the timetable you trust, and keep it consistent through the year.