Why do Shia Muslims break the fast later?
In Ramadan you may notice Shia friends opening their fast some minutes after the sunset adhan from a Sunni mosque, usually 15 to 30. It isn't extra devotion or a different fast. The fast ends at Maghrib, and Ja'fari practice puts Maghrib a little after sunset.
The end of the day
The Qur'an says to complete the fast "until the night" (2:187). Every school agrees on that. They differ on the sign that night has come.
Many Sunni schools take the sun's disc going below the horizon. Most Shia jurists take the moment the red glow that rises in the eastern sky after sunset has passed overhead. That happens when the sun is about 4° below the horizon.
How much later?
About 13 minutes after sunset near the equator, 20 to 30 in London, and close to an hour in Oslo in June. The gap is real, and it changes with the season and your latitude. Each city page on this site gives its own range through the year.
If your family follows another time
This is a difference in how jurists derive the ruling, and it is handled with respect on both sides. If you follow a Shia marja', you open your fast at Maghrib as they define it. Sitting at the table with family who open earlier is fine. Wait the few minutes and join them.
How the app calculates it
Shia Namaz gives Maghrib from the sun's angle below the horizon, 4° with Qom or 4.5° with Tehran, and keeps sunset as a separate row so you can see the gap.
Get the app Shia Namaz shows sunset and Maghrib side by side, so you know when to open your fast, and works offline.
See today's iftar time for your city →
Next guide: what Imsak is, and when to stop eating →
Sources: Qur'an 2:187. Office of Ayatollah al-Sistani, Islamic Laws, on the times of Maghrib. Other marja' may define the sign of Maghrib a little differently.