Why prayer times differ

Two apps, or an app and the local mosque, often disagree on Fajr and Isha: in London they are up to 48 minutes apart today. Usually nobody is wrong: they follow different conventions.

1. Fajr and Isha: how far below the horizon the sun is

Fajr begins at dawn, when light first appears, and Isha when twilight has gone. To compute them you must decide how far below the horizon the sun is at that moment, and organisations choose different values: 18° for the Muslim World League and Karachi, 15° for ISNA, a seasonal rule based on observations for the Moonsighting Committee. In the UK one degree is about 6 to 7 minutes.

In London, with each method:

Method Fajr todayIsha today Fajr in JuneIsha in June
Moonsighting Committee (seasonal) 05:0917:47 02:4322:41
Muslim World League (18° / 17°) 04:5318:29 03:40*22:25*
Karachi, South Asia (18° / 18°) 04:5318:35 03:40*22:25*
ISNA, North America (15° / 15°) 05:1218:16 03:40*22:25*

Today: 27 Oct · June: 21 Jun. * High-latitude rule.

2. Asr: one or two shadow lengths

The Shafi‘i, Maliki and Hanbali schools pray Asr when an object’s shadow equals its length (plus the noon shadow); the Hanafi school when it is twice its length. Today in London the Hanafi Asr is 40 minutes later. Many UK timetables print both.

3. Summer nights in the north

In London from about late May to late July, and for longer further north, the sun does not go 18° below the horizon, so dawn and dusk meet. A high-latitude rule then sets Fajr and Isha: the middle of the night, one seventh of the night, or a share based on the angle; the Moonsighting Committee uses its own seasonal limits. Each gives a different time, and we say next to the time when a rule applies. In London on 21 June they are 57 minutes apart (the June columns).

4. Dhuhr and Maghrib: a few minutes of caution

Dhuhr follows the sun crossing the meridian and Maghrib follows sunset. Some methods add one to a few minutes as a precaution, which explains small differences.

5. Your mosque’s timetable

Many mosques publish their own timetable, sometimes fixed for the year, and the congregational prayer (jama‘ah or iqamah) comes some minutes after the start time. To pray in congregation, follow your mosque’s timetable; praying alone, pick a method and keep to it.

See the prayer times for London →