Prayer times are not looked up in a table. They are computed from the sun's position for your exact coordinates, and that computation takes parameters. Change a parameter and the answer moves — legitimately, for everyone using that parameter.
The two parameters that cause almost all disagreement
Fajr begins at true dawn and Isha at the end of twilight. Neither moment has a single agreed definition, so each authority fixes an angle: how far the sun is below the horizon. A larger angle means an earlier Fajr and a later Isha.
| Authority | Fajr angle | Isha angle | Used in |
|---|---|---|---|
| Muslim World League | 18° | 17° | Europe, much of the world |
| Diyanet İşleri Başkanlığı | 18° | 17° | Türkiye |
| Umm al-Qura, Makkah | 18.5° | 90 min after Maghrib | Saudi Arabia |
| Egyptian General Authority | 19.5° | 17.5° | Egypt, Syria, Lebanon, Iraq |
| University of Islamic Sciences, Karachi | 18° | 18° | Pakistan, India, Bangladesh |
| ISNA | 15° | 15° | United States, Canada |
| JAKIM | 20° | 18° | Malaysia, Indonesia, Singapore |
ISNA's 15° is the outlier and the reason North American timetables often show a noticeably later Fajr than the ones a family brought with them from elsewhere. Neither is a mistake; they are answering the same question with different thresholds.
Asr: the one that moves by an hour
Asr begins when an object's shadow reaches a set multiple of its own length, measured after the minimum shadow at noon. The Hanafi school uses twice the object's length; the Shafi'i, Maliki and Hanbali schools use once.
In mid-latitudes the gap between the two Asr calculations runs from roughly 45 minutes in summer to over an hour in winter.
This is why an app can look wrong to two people in the same room. If your app shows Asr about an hour before your mosque, you are probably on the majority calculation while your mosque follows the Hanafi one, or the reverse.
What to check when the times look wrong
- Check the location the app is using. A cached city from a trip will shift everything.
- Check which calculation method is selected, and compare it against what your local mosque or national authority publishes.
- Check the madhhab setting if it is Asr that looks off by around an hour.
- Check for a high-latitude rule if you are above roughly 48° and it is summer — Fajr and Isha may be approximated rather than computed.
- Only then adjust individual prayers by hand, a minute or two at a time.
Above 48°: when twilight never ends
North of roughly 48° latitude in summer, the sun never drops far enough below the horizon for astronomical Fajr or Isha to occur at all. No angle produces an answer, so calculation methods substitute a rule — dividing the night into sevenths, taking the closest date at which the angle does occur, or using a fixed interval after Maghrib. Communities in the same city may follow different rules, which is why mosque timetables in Northern Europe can differ by an hour or more in June.