A common, harmless gap
It is very normal for a prayer app and a local mosque to differ by a few minutes. This rarely signals an error on either side — it usually comes down to a handful of well-understood reasons. Here is what is going on.
1. Different calculation methods
As covered in our methods guide, Fajr and Isha depend on a chosen twilight angle (15°, 17°, 18°, 18.5°…). If your mosque follows one convention and your app another, the two will differ — most visibly at Fajr and Isha. Matching your app to the local method removes most of the gap.
2. Beginning of the window vs. congregation time
A calculated time marks the start of a prayer's window. A mosque, however, schedules its congregation (jamaah) a little later so people can gather. So a board reading "Dhuhr 1:30" may be the jamaah time, while your app shows the earlier moment the window opened. Both are right; they answer different questions.
3. Safety margins
Many mosques add a precautionary minute or two — especially to Fajr (starting slightly later) and Maghrib (breaking the fast slightly after sunset) — to be sure the prayer is within its time. These deliberate buffers create small, intentional differences.
4. The Hanafi vs. Standard Asr
If your mosque follows the Hanafi school, its Asr will be later than the Standard timing, because Hanafi Asr begins when a shadow is twice an object's length rather than equal to it. An app set to the Standard method will look "early" by comparison.
5. Rounding and fixed annual tables
Some mosques print one fixed table for the whole year, or round every time to the nearest five minutes for simplicity. A daily-calculated app updates to the exact minute, so the two naturally drift apart by small amounts.
Which should you follow?
For praying in congregation, follow your mosque's announced jamaah times. For knowing when a prayer's window opens and closes — useful when praying at home, work or while travelling — a per-day calculation like SalatWaqt's is ideal. Used together, they complement rather than contradict each other.
A worked example
Say your app shows Dhuhr beginning at 1:12 pm, but the board at your mosque reads 1:30 pm. There is no conflict: 1:12 pm is when the Dhuhr window opens (just after solar noon), and 1:30 pm is when the mosque has chosen to hold the congregation so worshippers can arrive. If you pray at home at 1:15 pm you are perfectly on time; if you join the jamaah you simply come for 1:30 pm. The same logic explains an Asr board time that looks "late" — it may be the Hanafi timing, or the jamaah slot, or both.
How to reconcile the two
If you want your app and mosque to match as closely as possible, take three steps. First, set your app to the calculation method your country and mosque use — this removes the largest gaps, which are almost always at Fajr and Isha. Second, choose the Asr school (Standard or Hanafi) that your mosque follows. Third, remember that the remaining difference is usually the deliberate gap between a window opening and the congregation gathering, plus any small safety margin. After those adjustments, a difference of more than a few minutes is rare.
The takeaway
A few minutes' difference is expected and acceptable. If the gap is ever large (more than, say, ten to fifteen minutes at Fajr or Isha), it is almost always a mismatched calculation method — adjust the method and the times will fall back into line.