How Prayer Times Are Calculated

The five daily prayers are among the most precise obligations in Islam — each tied to the sun's exact position in the sky. But if you have ever compared two prayer apps side by side, you may have noticed Fajr showing 4:12 in one and 4:26 in the other. The reason comes down to mathematics, geography, and centuries of scholarly effort to standardize the heavens.

The Astronomy Behind Salah

Each prayer begins when the sun crosses a specific angle below or above the horizon:

• Fajr — begins when the sun is between 15° and 18° below the horizon (before sunrise). Astronomers call this the solar depression angle. This is the "true dawn" (al-fajr al-sadiq), when the first light spreads horizontally across the sky — distinct from the false dawn (al-fajr al-kadhib), which appears vertically.
• Dhuhr — begins just after the sun passes its zenith (solar noon), when shadows start lengthening again.
• Asr — begins when the shadow of an object equals its height (Shafi'i/Maliki/Hanbali) or twice its height (Hanafi). This is the most common difference between the two major madhabs.
• Maghrib — begins at sunset, when the upper limb of the sun disappears below the horizon.
• Isha — begins when the red twilight (al-shafaq al-ahmar) disappears, typically when the sun is 15°–17° below the horizon.

“Establish prayer at the decline of the sun until the darkness of the night, and [also] the Quran of dawn — indeed, the recitation of dawn is ever witnessed.”

Surah Al-Isra 17:78

Why Different Methods Give Different Times

The disagreement is almost entirely about Fajr and Isha — the two prayers calculated from twilight. Different scholarly bodies have measured the sky at different latitudes and reached slightly different conclusions about where "true dawn" and "true darkness" begin.

The Hanafi vs. Shafi'i Difference for Asr

The Hanafi school delays Asr until the shadow of an object reaches twice the object's height beyond the noon shadow, which typically adds 30–60 minutes compared to the Shafi'i, Maliki, and Hanbali position (shadow equals the object's height beyond noon shadow). Both are valid scholarly positions established from hadith. The difference matters most in summer months at higher latitudes.

A Note on the ISNA 15° Method

The Islamic Society of North America (ISNA) uses 15° for both Fajr and Isha — lower than the 18° used by many other organizations. This reflects a 2004 resolution by the Fiqh Council of North America, based on commissioned astronomical research showing that 18° produces excessively early Fajr and excessively late Isha times at North American latitudes, particularly in summer. If your previous app used 18° for North America and you switched to one using ISNA's 15°, the 15–20 minute difference in Fajr and Isha is intentional and scholarly.

Which Method Should I Use?

Follow your local mosque or the official body of your country:

• Turkey — Diyanet (Presidency of Religious Affairs)
• Saudi Arabia and Gulf — Umm al-Qura
• North America — ISNA
• Pakistan, India, Bangladesh — Karachi
• Iran — Tehran (Institute of Geophysics)
• Egypt and North Africa — Egyptian General Authority
• Europe, international — Muslim World League

The Tuba prayer times calculator detects your location and suggests the most appropriate method automatically, while letting you switch freely between all methods.

Practical Notes for High Latitudes

At latitudes above approximately 48°N (northern Europe, northern Canada), twilight in summer may persist all night — meaning Fajr and Isha technically never occur by astronomical definition. Scholars have developed several conventions to handle this: the "nearest latitude" method (borrowing the twilight angle from the nearest city where it is calculable), the "nearest day" method (using the last day on which the prayer time could be calculated), and the "one-seventh of the night" method. Most prayer time applications default to one of these when standard calculation is not possible.

Frequently Asked Questions

Why does my prayer app show a different Fajr time than my local mosque?

The most common reason is a different calculation method. Your local mosque may follow Diyanet, ISNA, or a regional authority that uses slightly different solar depression angles. A difference of 10–20 minutes for Fajr or Isha is normal across methods. Check which method your mosque follows and set the same in your app.

Which prayer time method is most accurate?

All the major methods — Diyanet, Muslim World League, ISNA, Egyptian, Karachi, Umm al-Qura — are astronomically accurate. They differ in their scholarly definition of when "true dawn" begins, not in their astronomical calculations. Use the method endorsed by the official Islamic authority in your country or region.

Why is Asr later on some apps than others?

Asr timing differs between the Hanafi school (shadow = twice the object's height) and the Shafi'i, Maliki, and Hanbali schools (shadow = the object's height). Hanafi Asr is typically 30–60 minutes later. If you are Hanafi, ensure your app is set to the Hanafi madhab for Asr.

Does prayer time calculation use the Islamic calendar?

No. Prayer times are calculated from the sun's position relative to your geographic coordinates on any given day of the Gregorian calendar. The Islamic (Hijri) calendar determines the start of Ramadan, Eid, and other religious dates, but not daily prayer times.