How Are Islamic Prayer Times Calculated?
Islamic prayer times are calculated based on the precise astronomical position of the sun. The five daily prayers (Fajr, Dhuhr, Asr, Maghrib, and Isha) correspond to specific solar events: dawn, solar noon, afternoon shadows, sunset, and nightfall.
If you've ever used a prayer times calculator, you might have noticed different options like "ISNA", "MWL", or "Umm Al-Qura". Why are there different methods, and which one should you use? Let's break down the science and geography behind the Adhan schedule.
Quick Summary: In the United States, the ISNA (Islamic Society of North America) method is the standard. It calculates Fajr and Isha when the sun is 15 degrees below the horizon.
The 5 Prayers and the Sun
The time for each prayer is universally defined by the sun's journey across the sky:
- Fajr (Dawn): Begins when the true dawn appears (morning twilight) and ends exactly at sunrise.
- Dhuhr (Midday): Begins immediately after the sun passes its zenith (the highest point in the sky) and begins to decline.
- Asr (Afternoon): Begins when an object's shadow equals its height (plus the shadow's length at Dhuhr). There are slight variations between Hanafi and Shafi'i schools on this exact calculation.
- Maghrib (Sunset): Begins exactly when the sun completely disappears below the horizon.
- Isha (Night): Begins when the red twilight disappears from the sky entirely, marking true night.
Why Do Calculation Methods Differ?
While Dhuhr, Asr, and Maghrib are relatively straightforward to calculate based on solar noon and sunset, Fajr and Isha rely on twilight.
Twilight is determined by the angle of the sun below the horizon. Because twilight looks different depending on your latitude and the season, various Islamic organizations have established different standard angles to calculate when "true dawn" and "true night" occur.
Major Calculation Methods
- ISNA (Islamic Society of North America): Uses 15 degrees for both Fajr and Isha. This is the default and most accurate method for North America.
- MWL (Muslim World League): Uses 18 degrees for Fajr and 17 degrees for Isha. Commonly used in Europe, the Far East, and parts of the US.
- Umm Al-Qura (Makkah): Uses 18.5 degrees for Fajr. For Isha, it sets a fixed time of 90 minutes after Maghrib (120 minutes during Ramadan). Used in the Arabian Peninsula.
- Egyptian General Authority of Survey: Uses 19.5 degrees for Fajr and 17.5 degrees for Isha. Used primarily in Africa and parts of the Arab world.
How Do I Choose?
If you live in the United States, we recommend leaving your settings on the ISNA calculation method. Our USA prayer times tracker defaults to ISNA to ensure your daily salat schedule matches the vast majority of local mosques across America.