The five daily prayers in Islam are tied to the sun's position, not fixed clock times. This is why prayer times change every day, vary significantly by latitude, and why a Muslim in Karachi and a Muslim in Oslo have dramatically different prayer schedules even on the same day. Understanding the astronomical basis helps Muslims appreciate this system and explains why different apps sometimes show slightly different times for the same location.
The Five Salah Times and Their Definitions
Fajr (Dawn prayer): Begins at astronomical twilight when the sun is at a specific angle below the horizon — typically 15 degrees or 18 degrees depending on the calculation method — and the first hint of light appears in the east. Ends at Sunrise.
Dhuhr (Midday prayer): Begins when the sun crosses the local meridian (solar noon — the highest point in the sky that day). Exact time varies by longitude and time of year due to the equation of time.
Asr (Afternoon prayer): Begins when the shadow of an object equals its own length plus its noon shadow (Shafi'i method), or twice its length plus noon shadow (Hanafi method). This is why Hanafi Asr is always later than Shafi'i Asr.
Maghrib (Sunset prayer): Begins immediately at sunset when the sun's upper edge disappears below the horizon. All major schools agree on this definition.
Isha (Night prayer): Begins when the red twilight in the west disappears — when the sun is approximately 15-18 degrees below the horizon. This is the evening equivalent of Fajr's dawn calculation.
Why Prayer Times Differ by Location
Every location has a different solar noon time, different shadow change rates, and different sunrise and sunset times — all determined by latitude and longitude. At high latitudes above 45 degrees north (most of Europe), summer Isha can be extremely late or the sun may not reach the required angle below the horizon at all. Islamic scholars have developed several methods for high-latitude prayer times.
At Pakistani latitudes (24-37 degrees north), prayer times are more consistent year-round, though summer and winter Fajr and Isha can still differ by 1-2 hours.
Why Different Apps Show Different Times
Different organizations use slightly different twilight angles for Fajr and Isha:
University of Islamic Sciences Karachi (UISK): Fajr at 18 degrees, Isha at 18 degrees. This is the standard method used in Pakistan and matches most mosque timetables.
Muslim World League (MWL): Fajr at 18 degrees, Isha at 17 degrees. Used widely in Europe and globally.
ISNA (North America): Both at 15 degrees.
Umm al-Qura (Saudi Arabia): Fixed 90-minute offset after Maghrib for Isha.
In Pakistan, the UISK method matches official announcements from the Central Ruet-e-Hilal Committee and most mosques. If your app uses a different method, its Fajr and Isha times will differ slightly from local mosque timetables.
Atmospheric Refraction and Elevation
Prayer calculations also account for atmospheric refraction — the bending of sunlight as it passes through the atmosphere. This adds approximately 2-3 minutes to visible sunrise compared to geometric calculation. Elevation above sea level also affects times — at higher altitudes, the horizon is effectively lower, so sunrise appears earlier and sunset later. Major prayer time algorithms include elevation correction.
Conclusion
Prayer times are precise astronomical calculations, not arbitrary clock times. The variation between apps comes from different twilight angle conventions, not errors. For Pakistan, the UISK method at 18 degrees for both Fajr and Isha matches official mosque timetables most closely. Use our prayer times calculator with your exact coordinates for the most accurate results for your location.