You open one prayer app and Fajr is at 5:12. Another says 5:26. Your masjid's timetable says something else again. None of them is broken. They are using different calculation methods, and the differences are predictable once you know where they come from.
Prayer times are astronomy plus a choice
Dhuhr and Maghrib are easy: Dhuhr starts just after the sun passes its highest point, and Maghrib at sunset. Those barely vary between apps.
Fajr and Isha depend on twilight, and Islamic scholarship does not fix a single sun angle below the horizon for when dawn begins or night is fully dark. So each authority picks an angle. Commonly used methods:
| Method | Fajr angle | Isha |
|---|---|---|
| Muslim World League (MWL) | 18° | 17° |
| ISNA (North America) | 15° | 15° |
| Egyptian General Authority | 19.5° | 17.5° |
| University of Islamic Sciences, Karachi | 18° | 18° |
| Umm al-Qura (Makkah) | 18.5° | 90 minutes after Maghrib (120 in Ramadan) |
A 15° Fajr (ISNA) is later than an 18° Fajr (MWL), by roughly 15 to 30 minutes depending on your latitude and the season. That is the whole story behind most "my two apps disagree" moments.
Asr has two valid rules
Asr begins when an object's shadow reaches a set length. The Shafi'i, Maliki and Hanbali schools use one times the object's height (plus its noon shadow). The Hanafi school uses two times. The Hanafi Asr is therefore noticeably later, often 45 to 75 minutes. If you follow Hanafi fiqh and your app is set to the standard rule, you may be praying before your Asr time begins.
How to choose the right setting
- Follow your local masjid. If you pray with a community, match their timetable. Find the method they publish and select the same one.
- Otherwise use your region's norm. ISNA is common in the US and Canada, MWL in Europe and much of the Middle East, Karachi in South Asia, Egyptian in Africa, Umm al-Qura in Saudi Arabia.
- Set Asr to your madhhab. Hanafi or standard.
- At high latitudes twilight may never end in summer; many masjids use a fixed-fraction rule there. Follow your local scholars.
Check it in Athan
Athan computes prayer times on your phone from your location, so it works offline and does not send your position anywhere. It offers five calculation methods (ISNA, Muslim World League, Umm al-Qura, Egyptian, Karachi) and a Hanafi/Shafi'i toggle for Asr, so you can line it up with your masjid in under a minute.
Pick the method, compare the first day with your timetable, and you are done. If the times match, you can stop second-guessing every app you open.
Prayer times are a tool, not a ruling. When in doubt, ask your imam.