Why prayer-time apps disagree

The times the sun fixes

Sunrise, midday (Dhuhr) and sunset (Maghrib) are set by the sun itself, so every careful timetable agrees on them to within a minute or two. Small differences come from rounding, from a minute or two added for safety, and from whether the timetable allows for the height of the place.

Fajr and Isha: how dark is dark

Fajr begins at true dawn and Isha when the twilight has gone. Neither moment can be seen on a clock, so each method picks how far the sun must be below the horizon, in degrees:

• University of Islamic Sciences, Karachi: 18 degrees for both Fajr and Isha.
• Muslim World League: 18 for Fajr, 17 for Isha.
• ISNA (North America): 15 for both.
• Umm al-Qura (Makkah): 18.5 for Fajr, and Isha 90 minutes after Maghrib.

A few degrees matter. In Kabul, the gap between the 15 and 18 degree methods is around a quarter of an hour for Fajr, and more in summer, when the twilight lasts longest.

Asr: one shadow or two

Asr begins when an object's shadow reaches a set length. In the Hanafi school, followed by most Afghans, that length is twice the object's height (plus its shadow at noon). Most other schools use once the height. The Hanafi Asr is later, in Kabul by about 40 minutes in winter and over an hour in summer. An app set to the other school will show Asr far too early for a Hanafi reader.

Where you are

The whole country keeps Kabul time (UTC+4:30), but the sun does not. Herat lies about seven degrees of longitude west of Kabul, so every prayer there comes roughly 28 minutes later by the clock. A timetable for Kabul is wrong for Herat, Kandahar or Faizabad, and even within a large city the edges differ from the centre by a minute or so.

What this site does

Prayer times here use the Karachi method, 18 degrees for Fajr and Isha, with the Hanafi Asr: the method in common use in Afghanistan. They are calculated for each provincial capital, or for exactly where you are if you allow your location. If your mosque's timetable differs by a minute or two, follow your mosque: it may add a precaution, and it is the local authority on the matter.

If an app shows Asr an hour earlier than your mosque, look for its "Asr method" or "juristic method" setting and choose Hanafi.