How We Calculate Prayer Times

When does Fajr begin?

This is the first prayer of the day, at dawn. Islamic tradition distinguishes two different times for dawn: when the first light appears at the horizon, rather vertical — “like the tail of a wolf,” as tradition describes it — and then, after this first light disappears, when the light of the early day spreads horizontally across the horizon. The first is called Subh Kādhib (false dawn), and the second Subh Sādiq (true dawn). Fajr is prayed at the second, Subh Sādiq.

In earlier times, Muslims skilled in the field could recognise true dawn by eye. Today, with light pollution and a decline in that expertise, it is more accurate to calculate it using scientific instruments and astronomical data, interpreted for our ease.

According to Hanafi ulema with expertise in this field, Subh Sādiq is calculated in terms of degrees when the centre of the Sun is a given number of degrees below the horizon. 15° and 18° are among the commonly adopted values. Lancaster Islamic Society has chosen to utilise the 15° opinion — the same figure recommended by the Fiqh Council of North America (ISNA's religious affairs body) for both Fajr and Isha. Other mosques may use a different recognised angle, so a difference between timetables does not necessarily indicate an error.

Deep-summer Fajr in Lancaster

For around ten weeks either side of the summer solstice, true dawn never reaches 15° below the horizon at Lancaster's latitude — the sky stays too light overnight. During this window, Fajr is instead calculated using the Angle-Based Method: the night is divided proportionally according to the same 15° figure, and Fajr falls one-quarter of the way through the night before sunrise.

This keeps Fajr on a smooth, sensible schedule through the deep-summer weeks rather than leaving it undefined, and hands back to the direct 15° calculation once true dawn becomes reliably distinguishable again in late summer.

When does Dhuhr begin?

The midday prayer. Just as the Sun declines after reaching its highest position in the sky (zenith), Dhuhr is prayed approximately five minutes after zenith.

Dhuhr has been defined in several ways in the fiqh literature:

1. When the Sun begins to decline (zawāl) after reaching its highest point in the sky.
2. When the shadow of an indicator (a vertical stick) reaches its minimum length and starts to increase.
3. When the Sun’s disk comes out of its zenith line — the line between the observer and the centre of the Sun when it is at its highest point.

The first and second definitions are equivalent, since shadow length correlates directly with the Sun’s elevation. By the third definition, it takes approximately one minute for the Sun’s disk to clear its zenith line, and this is factored into the Dhuhr calculation.

Dhuhr technically begins once zawāl has occurred. Lancaster Islamic Society publishes the time five minutes after calculated solar noon as a brief ihtiyāṭ. The five minutes are a precaution, not part of Dhuhr’s intrinsic Sharʿī definition.

When does Asr begin?

The mid-afternoon prayer. Asr’s beginning is determined using an object’s afternoon shadow, and within the Hanafi school there are two well-known views:

Lancaster Islamic Society follows the second-shadow view: Asr begins once an object's shadow has grown by twice its own height, counted on top of the shadow it already casts at solar noon (fayʾ al-zawāl). For example, a one-metre stick that already has a 10 cm shadow at solar noon reaches second-shadow Asr once its total shadow reaches 2.10 metres — the original 10 cm, plus two full metres.

Many prayer apps default to first shadow. Selecting the “Hanafi” Asr setting will usually produce the later second-shadow time used by Masjid al-Noor.

When does Maghrib begin?

The prayer at sunset. In fiqh, Maghrib is defined as actual sunset, taking into account three things: variation in atmospheric refraction, the precise latitude and longitude used, and any downward-sloping ground towards the direction of sunset.

It is generally accepted as occurring around three minutes after theoretical (calculated) sunset.

On our timetable we calculate Maghrib as sunset (Lancaster) plus four minutes — a slightly cautious ihtiyāṭ allowing sunset to fully commence. The Sharʿī beginning of Maghrib remains actual sunset; it is not intrinsically defined as four minutes later.

When does Isha begin?

The night prayer at dusk. Just as for Fajr, Islamic tradition distinguishes two phases of dusk, both called shafaq (twilight). After sunset the sky first glows red — Shafaq al-Aḥmar. Later this red colour disappears, leaving a whiteness in the sky — Shafaq al-Abyaḍ. The duration of both phases increases with latitude.

The major schools fix Isha at the disappearance of either Shafaq al-Aḥmar or Shafaq al-Abyaḍ; both are legitimate positions, and — as with Asr — the choice is left to the individual mosque. At higher latitudes, adjustment is necessary because Shafaq al-Abyaḍ almost never fully disappears in summer. In such cases a combination (“Shafaq General”) or another consensus-backed method is used instead.

Winter Isha in Lancaster

According to Hanafi ulema with expertise in this field, Isha — like Fajr — can be calculated in degrees below the horizon. Lancaster Islamic Society uses the 15° opinion, which works well during the winter months.

Summer Isha in Lancaster

Lancaster sits at approximately 54.05° North — close to the band of latitudes (roughly 55° to 60°) where Fajr and Isha times draw very close together and degree-based methods can produce times that become a genuine hardship (ḥaraj) for the public. For part of the year the same difficulty applies here too.

Lancaster Islamic Society follows the formula suggested by Wifaqul Ulama (Britain) for use in prayer-time software: calculate Isha both ways — at 15° below the horizon, and at one-seventh of the night — and adopt whichever gives the earlier time. For most of the year the two calculations are close and 15° is earlier, so that is what appears on the timetable. Around late March, as nights shorten, the one-seventh calculation becomes earlier and takes over; it remains in use through summer, then hands back to the 15° calculation around mid-September once nights lengthen again. This isn't a manual seasonal switch — it's the same rule applied every day, which is why the changeover date shifts slightly from year to year rather than falling on a fixed calendar date.

The one-seventh division is an approach to dividing the night also associated with Shafiʿi fiqh, applied here as an estimation for high-latitude conditions. It has been permitted by Shaykh Ashraf Ali Thanwi of India (Imdād al-Fatāwā, vol. 2, p. 98, dated 12/12/1322 Hijri) and also by Allamah Shami in Radd al-Muhtār (Durre Mukhtar). Mufti Shafi Usmani of Pakistan explained that this position rests on the premise that, in countries where Subh Sādiq cannot be clearly distinguished — such as Northern Europe in the summer months — it is permissible to act on this advice. It is not presented as the universal definition of Isha, but as an estimation method suited to high-latitude conditions.