How Prayer Times Are Calculated
What the calculator is actually doing
Every prayer time on this site is worked out from the position of the sun at your coordinates, on your date, in your time zone. There is no external service and no lookup table: the theme runs an astronomical calculation on your own server. That is why it works for any of the 4,884 cities in the database and for any date you ask it for.
The times that are not disputed
- Sunrise and sunset are geometric facts. Every method agrees.
- Dhuhr begins just after the sun passes its highest point. Again, no dispute.
- Maghrib begins at sunset, which is why iftar is not a matter of method either.
The times that are disputed, and why
Fajr and Isha depend on twilight, and twilight has no sharp edge. Fajr begins when the first true light appears along the horizon; Isha when the last of the evening light disappears. Astronomers express both as the sun being a certain number of degrees below the horizon — but which number is a judgement, and different bodies have settled on different ones.
- Muslim World League — 18° for Fajr, 17° for Isha.
- Umm al-Qura (Makkah) — 18.5° for Fajr, and Isha fixed at 90 minutes after Maghrib.
- Egyptian General Authority of Survey — 19.5° and 17.5°.
- University of Islamic Sciences, Karachi — 18° for both.
- ISNA — 15° for both, which is why North American timetables often show a noticeably later Fajr.
A few minutes of difference between two printed timetables for the same city is almost always this, and not an error in either.
The Asr rule
Asr is decided by shadow length rather than by an angle. In the standard view, followed by the Maliki, Shafi‘i and Hanbali schools, Asr begins when an object’s shadow equals its own length plus its shadow at noon. In the Hanafi view it begins when the shadow reaches twice the object’s length, which puts Asr noticeably later — often by 40 to 70 minutes depending on the season and latitude. Both are valid; the calculator lets you pick.
Choosing a method
The straightforward answer is to use whatever your local mosque uses, so your household and your congregation are on the same timetable. If you have no local reference, the site defaults to the method conventionally used in your country — Umm al-Qura in Saudi Arabia, Karachi in Pakistan and India, ISNA in North America, Muslim World League elsewhere.
High latitudes
Above roughly 48° north or south there are parts of the year when the sun never drops far enough below the horizon for true twilight to end. The angle-based rule then produces no Fajr or no Isha at all. Scholars have offered several solutions: taking the timings of the nearest location with a normal night, dividing the night into fixed portions, or following Makkah. Communities in those regions should follow the ruling their own scholars have adopted.
Frequently asked questions
Why is my Fajr time different from another app?
Almost certainly a different calculation method or a different Asr convention. Compare the method setting before assuming either is wrong.
Which method is the correct one?
None of them is uniquely correct. They are different reasonable judgements about the same natural phenomenon. Follow your local mosque.
What is imsak?
A precautionary margin of a few minutes printed before Fajr on some timetables. The Shari‘ah limit for eating is the entry of Fajr itself.