FajrPlus
Two apps, or an app and your mosque, can show Fajr several minutes apart for the same city on the same day. Neither has to be wrong. They use different calculation methods, and the difference comes down to one number: how far below the horizon the sun must be for dawn to count as having begun.
What Fajr is, in astronomy
Fajr begins at true dawn (al-fajr al-sadiq): the moment the first light spreads out along the eastern horizon, well before sunrise. Astronomically, that light appears when the sun is a certain number of degrees below the horizon. This is called the sun's depression angle.
Prayer time calculations take that angle and work out, for your latitude, longitude and date, the exact minute the sun reaches it. The deeper the angle, the earlier Fajr comes.
The methods and their angles
Scholars and institutions in different regions settled on different angles, based on observation and their own reasoning. Most lie between 15 and 20 degrees. These are the 11 methods FajrPlus offers, with the angle each uses for Fajr:
| Method | Fajr angle | Commonly used in |
|---|---|---|
| Muslim World League | 18° | Europe, the Far East, parts of the Americas |
| Umm al-Qura (Makkah) | 18.5° | Saudi Arabia |
| Egyptian General Authority | 19.5° | Egypt, much of Africa, parts of the Middle East |
| Karachi (University of Islamic Sciences) | 18° | Pakistan, India, Bangladesh, Afghanistan |
| Dubai | 18.2° | United Arab Emirates |
| North America (ISNA) | 15° | United States and Canada |
| Türkiye (Diyanet) | 18° | Türkiye |
| Kuwait | 18° | Kuwait |
| Qatar | 18° | Qatar |
| Singapore | 20° | Singapore, with similar angles in Malaysia and Indonesia |
| Moonsighting Committee | Seasonal | North America, the United Kingdom |
The Moonsighting Committee method does not use one fixed angle. It works out the gap between Fajr and sunrise from your latitude and the season, and above 55 degrees north or south it uses one seventh of the night instead. The methods also differ for Isha, which some set by angle and others as a fixed time after sunset, but that does not change Fajr.
How much difference it makes
This table shows roughly how many minutes before sunrise Fajr begins at each angle. The gap grows the further you are from the equator, and it is largest in summer.
| Place and day | 15° | 18° | 18.5° | 19.5° | 20° |
|---|---|---|---|---|---|
| Kuala Lumpur, 21 March | 57 | 69 | 71 | 75 | 77 |
| Makkah, 21 March | 61 | 74 | 76 | 80 | 83 |
| Makkah, 21 June | 70 | 85 | 88 | 93 | 96 |
| Cairo, 21 June | 78 | 97 | 100 | 106 | 109 |
| Istanbul, 21 March | 76 | 92 | 95 | 101 | 103 |
| New York, 21 June | 100 | 127 | 131 | 141 | 147 |
| London, 21 December | 104 | 124 | 128 | 134 | 138 |
| London, 21 June | 210 | not reached | not reached | not reached | not reached |
Minutes before sunrise, rounded. Worked out from the sun's position for each place and date; real timetables can differ by a minute or two.
So in Makkah the gap between the 15 and 19.5 degree methods is under 25 minutes, while in New York in June it is more than 40. That is why a method chosen for one country can feel far too early or too late in another.
Summer in the far north
In places like London, Amsterdam or Oslo, the sun in early summer never sinks 18 degrees below the horizon. The sky never gets fully dark, so an 18 degree Fajr simply never arrives. Timetables then fall back on a rule:
- Middle of the night: Fajr is no earlier than halfway between sunset and sunrise.
- One seventh of the night: Fajr begins in the last seventh of the night.
- Twilight angle: the night is divided in proportion to the angle, so an 18 degree method gives Fajr 18/60, or three tenths, of the night before sunrise.
FajrPlus uses the twilight angle rule, which is what many reference timetables use, and only where the sun really does not reach the angle.
Which method to choose
For praying on time with your community, the simplest answer is to use the method your local mosque uses. Compare your app with the mosque's timetable for a few days. If they match to the minute, you have found it. Some mosques also add a few minutes of caution to Fajr, so an exact match is not always possible.
If you have no local mosque, the method commonly used in your country is a reasonable start. These are calculated estimates, not religious rulings. Where they differ from your mosque or scholars, follow them.
Questions
Why is my app's Fajr time different from my mosque's?
Usually because they use different calculation methods, and so different angles for dawn. Some mosques also add minutes of caution. Pick the method your mosque uses and compare for a few days.
Which Fajr calculation method is correct?
Each method rests on the reasoning and observation of scholars in its region. For your daily prayer, the practical choice is the method your local mosque follows.
What does 18 degrees mean for Fajr?
It means Fajr begins when the sun is 18 degrees below the eastern horizon. At that point the first light of true dawn appears. A deeper angle, such as 19.5 or 20 degrees, gives an earlier Fajr.
Why is Fajr so early in summer?
In summer the sun rises earlier and, away from the equator, sinks less deeply below the horizon at night. Dawn light starts long before sunrise, so Fajr comes much earlier. In the far north the sun may not reach the dawn angle at all.