Understanding the Fajr angle — and why prayer apps disagree

The Fajr angle is the depression of the sun below the horizon at which Fajr begins. Different scholarly bodies adopt 15°, 17.5°, 18° or 19°, which is why apps differ by ten or twenty minutes.

Fajr (the dawn prayer) begins when the true dawn (al-fajr al-sadiq) appears across the eastern horizon. Modern prayer-time tables translate that observation into an astronomical quantity called the Fajr angle: how far the sun is below the horizon at that moment.

Why do calculation methods disagree?

The visible appearance of dawn varies slightly by latitude, climate, and air clarity. Each major scholarly body picked the angle they considered most defensible for their region:

Muslim World League (MWL): Fajr 18°, Isha 17°. Adopted as a global default.
ISNA (North America): Fajr 15°, Isha 15°. Reflects observed dawn in higher US/Canadian latitudes.
Umm al-Qura (Saudi Arabia): Fajr 18.5°. Isha is a fixed 90 minutes after Maghrib (120 in Ramadan), not an angle.
Egyptian General Authority: Fajr 19.5°, Isha 17.5°. The earliest Fajr of the major methods.
University of Islamic Sciences, Karachi: Fajr 18°, Isha 18°. Common across Pakistan, India, and Afghanistan.

At a typical mid-latitude city, the difference between 15° and 19.5° is roughly fifteen to twenty-five minutes for Fajr. This is why two prayer-time apps will give you different Fajr times for the same city.

Which one should you follow?

Use the method your local mosque uses. The five-pillar duty does not change between methods — the difference is purely the moment at which dawn is judged to have begun. Where you have no preference, MWL is the safe global default.

Sources

The numerical angles above are published by each scholarly body and aggregated by AlAdhan and the audited adhan-js library that QiblaWeb uses for computation (retrieved 2026-05-12).