How Are Prayer Times Calculated?

• Prayer times come from the sun's position where you are, not from a fixed calendar.
• Dhuhr, Asr and Maghrib are observable moments, so sources rarely differ on them.
• Fajr and Isha depend on a twilight angle, and methods choose different angles.
• Asr has two valid timings, depending on the school you follow.
• The best choice is usually the method your local mosque uses.

Prayer times are not picked by a committee or copied from a calendar. They are worked out from where the sun is in the sky above you, today, at your exact location.

That part is simple and nobody disagrees on it. The differences you see between apps, mosques and printed timetables come from a small number of choices made on top of that. Once you know what they are, the numbers stop looking arbitrary.

What Decides the Prayer Times?

Prayer times are decided by the position of the sun at your location. Dhuhr begins just after the sun passes its highest point, Asr when an object's shadow reaches a set length, and Maghrib once the sun has fully set. Fajr and Isha are tied to twilight, before sunrise and after sunset.

Given a date, a latitude and a longitude, astronomy can place those moments to within seconds. This is why Dhuhr and Maghrib almost never differ between sources by more than a minute or two.

“Indeed, prayer has been decreed upon the believers a decree of specified times.” Qur'an 4:103

Why Do Fajr and Isha Times Differ?

Fajr and Isha times differ between apps and timetables because twilight has no sharp edge. Each calculation method defines it by how far the sun sits below the horizon, measured in degrees, and the methods choose different angles. That is why two sources can show different times for the same city.

A larger angle means the sun is further below the horizon, the sky is darker, and so Fajr comes earlier and Isha comes later. A difference of three degrees can move Fajr by twenty minutes or more, depending on where you live and the time of year.

What Are the Main Calculation Methods?

A prayer time calculation method is a pair of twilight angles, one for Fajr and one for Isha, set by an authority and adopted across a region. The five you will meet most often are listed below with the angles each one uses.

• Muslim World League: Fajr 18°, Isha 17°
• Islamic Society of North America: Fajr 15°, Isha 15°
• Egyptian General Authority of Survey: Fajr 19.5°, Isha 17.5°
• Umm al-Qura, Makkah: Fajr 18.5°, Isha 90 minutes after Maghrib
• University of Islamic Sciences, Karachi: Fajr 18°, Isha 18°

Why Are There Two Asr Times?

There are two Asr times because the schools of law differ on how long a shadow must be before Asr begins. The Shafi'i, Maliki and Hanbali schools use one shadow length. The Hanafi school uses two, which places Asr later in the afternoon.

1. Shafi'i, Maliki and Hanbali. Asr begins when an object's shadow equals its own length, plus its shadow at midday.
2. Hanafi. Asr begins when the shadow is twice the object's length, plus its shadow at midday, which makes it later.

Which Method Should You Follow?

Follow the method your local mosque or community uses. Every method is an attempt to describe the same sky, and praying alongside the people around you matters more than a few minutes either way. If you are not sure which one your mosque follows, ask the imam or check its timetable.

Once you know, set the same method in your app and the two will agree.