Prayer Time Calculation Methods Compared

If you have ever noticed that two prayer-time apps show Fajr a few minutes apart, you have run into calculation methods. All of them use the same astronomy; they just make different choices about a couple of values. Here is what actually changes, and why.

What every method has in common

Dhuhr, Asr, and Maghrib are defined by the sun's height and shadows, so almost every method agrees on them. Dhuhr is just after the sun's highest point, Maghrib is at sunset, and Asr is when shadows reach a set length. These rarely differ between methods by more than a minute.

What the methods actually change: Fajr and Isha angles

The real difference is in Fajr and Isha, which are defined by how far below the horizon the sun sits (the "twilight angle"). A larger angle means an earlier Fajr and a later Isha. The main methods differ mostly here:

• ISNA (Islamic Society of North America) — Fajr and Isha at 15 degrees. The most widely used method in the United States and Canada.
• Muslim World League (MWL) — Fajr at 18 degrees, Isha at 17 degrees. Common in Europe and parts of the world beyond North America.
• Umm al-Qura (Makkah) — Fajr at 18.5 degrees, with Isha set as a fixed interval (about 90 minutes) after Maghrib. Used in Saudi Arabia.
• Egyptian General Authority — Fajr at 19.5 degrees, Isha at 17.5 degrees.

The Asr calculation (Standard vs Hanafi)

There is one more choice: Asr. The majority (Standard) opinion sets Asr when an object's shadow equals its own length plus the shadow at noon. The Hanafi opinion uses twice the object's length, which pushes Asr later. This is a school-of-thought difference, not a regional one.

Which method should you use?

If you are in North America, ISNA is the standard and the safest default, which is why MosqueIndex calculates every mosque's times with it. If your local mosque follows a different method, follow your mosque; consistency with your community matters more than a few minutes of difference.

Why "most accurate" is the wrong question

No method is objectively "most accurate," because the differences reflect scholarly conventions, not measurement error. The most useful times are the ones your local mosque uses. To see calculated times for a specific place, browse mosques near you and open any listing.