How prayer times are calculated

The sun, not a clock

The five daily prayers are tied to moments in the sun's passage across the sky, so a prayer time is really an astronomical calculation. Work out where the sun is for a given latitude, longitude and date, and you have the times. Because the sun's path changes through the year and differs from place to place, the times shift a little each day and are specific to your location. There is no single universal timetable.

Where each prayer comes from

• Fajr begins at true dawn, when the sky first starts to lighten. This is defined as the sun reaching a set angle below the horizon before sunrise.
• Sunrise is not a prayer. It marks the end of the time for Fajr, which is why most timetables list six entries even though five are prayers.
• Dhuhr begins just after the sun crosses its highest point for the day, known as solar noon.
• Asr begins when an object's shadow reaches a certain length. There are two long-standing conventions for that length, described below.
• Maghrib begins at sunset.
• Isha begins at nightfall, once the twilight after sunset has faded. Like Fajr, it is defined by a set angle of the sun below the horizon.

Why two apps disagree: the twilight angle

Fajr and Isha depend on how far below the horizon the sun has to be for dawn to break or dusk to end. Different authorities settled on different angles, so the two ends of the day are where methods diverge most. These are conventions adopted by scholarly bodies, not disagreements about the sky itself.

The larger the angle, the earlier Fajr and the later Isha. A few minutes of difference between apps almost always traces back to this choice.

The Asr difference

Asr is set by shadow length, and here there are two positions, each followed by large communities. In the standard position, held by the Shafi, Maliki and Hanbali schools, Asr begins when an object's shadow equals its own length. In the Hanafi position, it begins when the shadow reaches twice the object's length, which falls later in the afternoon. Both are calculated the same way from the sun; they differ only in the shadow ratio. We show the times for whichever you choose and do not take a side.

Near the poles

At high latitudes in summer the sun never dips far enough below the horizon for a true dawn or nightfall, so the angle-based definitions of Fajr and Isha stop returning a real time. Several rules exist to approximate them in that case, such as using the times from the nearest sensible latitude, or dividing the night into parts. Most apps apply one of these automatically so the times remain usable.

Which calculation method does each country use?

Communities follow the calculation authority common in their region. The Muslim World League method, with a Fajr angle of 18 degrees and Isha of 17, is the international default used across Australia and much of Europe and Africa. North America commonly uses ISNA, the United Kingdom and Ireland the Moonsighting Committee, Saudi Arabia Umm al-Qura, Turkey Diyanet, and South Asia the University of Karachi method with the Hanafi position for Asr. ImanKeeper maps each country to its community's method rather than applying one global default, and labels the Asr position it uses. The table below lists the method and default Asr position ImanKeeper applies for each country it covers.

Where a country is not listed, ImanKeeper applies the Muslim World League method as a sensible international default. Method and Asr position are both adjustable in the app.

Why your mosque's board is different

Even using the same method, the times posted at a mosque often differ from a raw calculation. Communities commonly round to the nearest minute or five, set the adhan slightly after the calculated moment, and then hold the iqamah a fixed number of minutes later so the congregation can gather. So the calculation is a close baseline, and the mosque's posted times are the practice your community actually follows. Both are legitimate; they answer different questions.

What ImanKeeper does

ImanKeeper computes times on your device using the Muslim World League method with the standard (Shafi) position for Asr by default, and lets you change both the method and the Asr position. And when you want the exact times your community prays rather than a calculation, it matches your masjid, so the times on your phone line up with the times on the wall.

A note on scope

This guide explains how times are computed and the conventions behind them. It does not give religious rulings. For questions about which method to follow, or whether a particular prayer is valid, ask your local imam.

Common questions