How We Calculate Sehri Times

Astronomical Data Source

Sehri times are calculated using astronomical algorithms from the sunrise-sunset.org API, which implements NOAA (National Oceanic and Atmospheric Administration) algorithms. The calculation determines when the sun reaches specific angles below the horizon.

Why 18° Below the Horizon?

Islamic scholars historically defined Fajr as the moment when dawn light begins to spread across the horizon, described in Qur'an 2:187 as "the white thread becoming distinct from the black thread." Many Islamic authorities correlate this moment with the sun being approximately 18 degrees below the horizon, as this corresponds closely with the appearance of true dawn observed historically.

The Muslim World League (MWL) adopted 18° as a widely accepted reference point for Fajr calculations internationally. However, Islamic scholars across different regions interpret the precise moment of dawn differently, leading to legitimate variation in calculation methods.

Calculation Methods

Different Islamic authorities interpret the appearance of dawn differently based on scholarly tradition. All methods below are considered Islamically valid and widely adopted by Islamic organizations in different regions:

• MWL Standard (18°) — Widely adopted internationally
• ISNA (15°) — Common in North America and Europe
• Umm al-Qura (18.5°) — Used in Saudi Arabia and Gulf countries
• Diyanet (20°) — Used in Turkey and Southeast Asia

Note: The time difference between methods varies depending on your latitude and the season, as twilight duration changes throughout the year.

Location-Specific Adjustments

Sehri time varies based on your exact geographic location. Our calculations automatically account for:

• Latitude — Affects twilight length and dawn timing
• Longitude — Determines local solar time
• Timezone — Converts to local time using IANA database
• Elevation — Higher elevations may observe dawn slightly earlier because the horizon appears lower

Why Your Local Mosque May Differ

It's normal for mosque timetables to differ slightly from astronomical calculations. Common reasons include:

• Safety buffer — Many mosques add a precautionary margin
• Different location reference — Mosque coordinates may differ from your location
• Community practice — Some follow long-established schedules for consistency
• Different calculation method — Your mosque may use ISNA, Umm al-Qura, or Diyanet

Best practice: Confirm with your local mosque which calculation method your community follows, and use the same method for consistency with your community's practice.