Prayer Calculation Methodology | PrayerTimesUSA
Understand the astronomical and mathematical methodology behind our prayer time and Qibla calculations.
Calculation Methodology
Prayer times are defined by the position of the sun in the sky relative to your exact geographical coordinates on Earth.
ISNA Standard (North America)
By default, we use the Islamic Society of North America (ISNA) calculation method, as it is the most widely adopted standard across the US and Canada.
- Fajr: Calculated when the sun is 15 degrees below the horizon before dawn.
- Isha: Calculated when the sun is 15 degrees below the horizon after sunset.
- Dhuhr: Occurs when the sun reaches its zenith (highest point) and just begins to decline.
- Asr: Calculated using the Standard (Shafi'i, Maliki, Hanbali) method where an object's shadow equals its height (plus its noon shadow).
Qibla Calculation
We calculate the Qibla direction using the Great Circle (Haversine) Formula. This calculates the shortest distance across the surface of the spherical Earth from your city's latitude and longitude to the Kaaba in Mecca (21.4225° N, 39.8262° E). Because the Earth is round, the shortest path from the US to Mecca is actually North-East, not South-East.