How Riyadh's times are computed
For Riyadh (24.64° N, 46.77° E) Hourora computes the sun's position for each date and solves for each prayer: Fajr 18.5°, Isha 90 min after Maghrib (120 min in Ramadan). Asr uses the standard shadow rule. The times are shown in Arabian Standard Time, daylight saving included.
The default is the method usually published in Saudi Arabia: Umm al-Qura, Makkah. You can choose another method, the Asr rule and the high-latitude rule above; the choice is saved on this device.