Prayer times calculation methods: ISNA, MWL, and others explained

If you've ever compared prayer times from two different apps or websites, you've probably noticed the times don't always match. The reason? Different calculation methods. While Dhuhr, Asr, and Maghrib are relatively consistent, Fajr and Isha times can vary by 15-30 minutes depending on the method used.

Why Multiple Methods Exist

The core challenge is defining when "dawn" begins (for Fajr) and when "night" begins (for Isha). Both depend on the sun's position below the horizon, measured in degrees. Different Islamic organizations around the world have settled on different angles based on their observations and scholarly opinions.

The Major Calculation Methods

ISNA (Islamic Society of North America) - Fajr: 15° below horizon - Isha: 15° below horizon - Used in: United States, Canada - Best for: North American Muslims

ISNA is the default method for most prayer time calculators in North America. It produces reasonable times even at higher latitudes (like Seattle or Minneapolis) where larger angles can create extremely early Fajr times in summer.

MWL (Muslim World League) - Fajr: 18° below horizon - Isha: 17° below horizon - Used in: Europe, parts of Asia - Note: Fajr starts 10-15 minutes earlier than ISNA

The MWL method uses a larger Fajr angle, which means dawn starts earlier. This is the traditional angle used in classical Islamic astronomy.

Egyptian General Authority of Survey - Fajr: 19.5° below horizon - Isha: 17.5° below horizon - Used in: Africa, Middle East, parts of Asia - Note: The earliest Fajr times of the common methods

Umm al-Qura (Mecca) - Fajr: 18.5° below horizon (was 19° before 2023) - Isha: Fixed at 90 minutes after Maghrib (120 minutes during Ramadan) - Used in: Saudi Arabia, Gulf states

This method is unique because Isha time is not calculated from sun position but fixed relative to Maghrib.

University of Islamic Sciences, Karachi - Fajr: 18° below horizon - Isha: 18° below horizon - Used in: Pakistan, Bangladesh, parts of India

Which Method Should You Use?

The general rule: use the method accepted by your local Muslim community.

• In the US and Canada: Use ISNA (15°/15°). This is the standard.
• In the UK and Europe: MWL (18°/17°) is most common.
• In the Middle East: Umm al-Qura for Saudi Arabia, Egyptian for most other countries.
• In South/Southeast Asia: Karachi (18°/18°) or MWL.

The High-Latitude Problem

At latitudes above ~48°N (Seattle, London, Scandinavia), the sun may never dip 18° below the horizon during summer. This means Fajr and Isha technically never begin — a problem for the MWL and Egyptian methods.

Solutions include:
- Using ISNA's 15° angle, which works at most inhabited latitudes
- Nearest-latitude method: using times from the closest latitude where normal calculation works
- Seventh-of-the-night: dividing the night into seven parts and using fixed fractions

This is one reason ISNA's 15° angle is popular in North America — it avoids extreme times even in northern cities.

Our Calculator

Our prayer times calculator uses the ISNA method (15°/15°), which is appropriate for all US and Canadian cities. All calculations happen locally in your browser using the adhan library, the same engine used by many popular prayer time apps.

Check your city: New York · Chicago · Los Angeles · Houston · Dearborn.