About prayer time calculation
Islamic prayer times are derived from the sun's position relative to the horizon at a given latitude and longitude: Fajr and Isha are defined by how many degrees the sun sits below the horizon before sunrise and after sunset, Dhuhr begins just after the sun crosses its highest point, Asr begins once an object's shadow reaches a defined multiple of its height, and Maghrib follows sunset. Because the angle used for Fajr and Isha isn't fixed by scripture to a single number, different regional authorities and scholarly bodies publish their own conventions — which is why the same city can show slightly different times depending on which method you pick.
Calculation methods
Muslim World League
18° Fajr / 17° Isha — widely used default across much of the world.
ISNA
15° / 15° — common across North America.
Umm al-Qura
18.5° Fajr, Isha fixed 90 minutes after Maghrib — used in Makkah.
Egyptian General Authority
19.5° / 17.5° — common across Africa and parts of the Middle East.
University of Karachi
18° / 18° — common across South Asia.
Asr: Standard vs. Hanafi
Standard uses a 1x shadow-length rule (Shafi'i/Maliki/Hanbali); Hanafi uses 2x, giving a later Asr.