ummahsalah
Prayer times come from the position of the sun. That part is astronomy and it is settled. Almost everything people disagree about comes after that, and this page explains what and why.
Begins at dawn, when the first light appears. Astronomically this is the moment the sun reaches a certain depth below the horizon while still below it. Which depth is the first thing people differ on.
Begins just after the sun passes its highest point of the day. This is one of the two times almost everyone agrees on, because the sun crossing the meridian is directly observable. Most timetables add a minute or two of margin.
Fixed by shadow length rather than by a sun angle. Most schools hold that Asr begins when an object's shadow equals its own length plus whatever shadow it cast at noon. The Hanafi school uses twice the object's length, which gives a later time — typically 30 to 60 minutes later. This is the single largest difference on any timetable, which is why many mosques print both.
Begins at sunset. The most reliable time of the five, since the sun disappearing below the horizon is something you can simply watch happen.
Begins when the last of the twilight has gone. Like Fajr it depends on how far below the horizon the sun has sunk — and some communities instead use a fixed gap after Maghrib, often 90 minutes.
Fajr and Isha both depend on a chosen angle, and different bodies settled on different figures. Some common ones:
None of these is a rounding error or a mistake. They reflect real differences in how scholars judged when first and last light occur. A larger angle means a darker sky, which makes Fajr earlier and Isha later.
This site shows when each prayer begins — the astronomical start of the window.
Mosque timetables usually print two columns: when the prayer begins, and when the congregation prays. The congregation time is deliberately later, so that people have time to arrive. It is set by each mosque, not by any calculation.
If the time on your mosque's wall looks later than what you see here, this is very often the explanation, and neither number is wrong. They are answering different questions.
Above roughly 48° of latitude there is a stretch of summer when the sun never sinks far enough below the horizon for the sky to get properly dark. Fajr and Isha then have no observable moment at all.
On those days the times have to be derived rather than observed. The common approaches divide the night into portions — halves or sevenths — or scale the angle down. Communities genuinely disagree about which to use, and it is a question of religious judgement rather than astronomy.
When this happens, the site marks Fajr and Isha as estimated rather than quietly handing you a number as though it were observed. You can change the rule under Settings, Advanced.
Even with the same method, a printed timetable can differ from a calculation:
There is a case this cannot fully solve, and London is it. Its unified timetable is a published table rather than a formula, and the sun angle implied by it moves through the year. Measured against the East London Mosque calendar:
That summer compression is deliberate: it keeps Isha from drifting towards midnight during the weeks when true darkness never arrives. No fixed angle can express it, which is why this site offers the published London timetable as a separate option rather than pretending a calculation can stand in for it.
Elsewhere, the older caveat still applies. Some regions use an agreed timetable rather than a formula, and London is the clearest example. Its unified timetable — used by East London Mosque, London Central Mosque and most mosques inside the M25 — is a published table, and the sun angle implied by it is not constant through the year. No calculation can reproduce it exactly. Matching will line this site up with such a timetable today, but expect a few minutes of drift across a season.
The Match your mosque tool on the main page handles the rest. For Dhuhr and Maghrib it stores a minute adjustment, which is the right tool because the margin those prayers carry really is a constant.
For Fajr and Isha it does something different: it works out which sun angle would produce your mosque's time, and uses that angle from then on. This matters because the gap between two angles is not a constant number of minutes — it stretches and shrinks through the year. Near the equator that variation is only a minute or two. In London the gap between an 18° and a 19.5° Fajr ranges from 9 minutes to 48 across the year, so a fixed offset set in January would be badly out by spring.
The circle is the sun's full 24-hour path. The horizontal line is your horizon. Everything above the line is daylight; everything below it is the sun continuing on its way out of sight.
Fajr and Isha sit below that line, because that is literally where they happen — the sun is beneath the horizon at both. Sunrise and Maghrib sit exactly where the path crosses it.
Watch it across the year and the horizon line slides through the circle. In midsummer only a thin sliver of the path is below the line, which is the same fact as the short northern night. In midwinter only a small cap sits above it.
Built by Ryan Kalagin.