My app and mosque show different prayer times: a checking checklist

The most useful comparison follows a fixed order: entry label, date, location, local clock, calculation convention, Asr setting and published adjustments. This article turns that order into a worksheet. It does not choose a religious method for you or assume a phone should overrule your mosque.

Start with one date and two identifiable sources

Save the mosque’s original timetable rather than a cropped image circulating without its heading. Record its name, year, coverage area and whether a newer version is available. Beside it, capture your app’s selected date, place and settings. Keep account details and unrelated notifications out of anything you send for help.

Choose one ordinary day first, then a second date if you need to check whether a proposed explanation holds. Avoid changing several options while gathering evidence: doing so makes it difficult to identify which change produced a result. Write down the original settings so a test does not become an undocumented permanent choice.

Use identical labels on your comparison sheet. Record Fajr beginning against Fajr beginning, not sunrise; record a mosque’s congregation separately. A source that gives only one number under a prayer name needs clarification before it can be compared fairly.

A worked comparison, not a real timetable

Consider this invented example. Its numbers illustrate the checking process and must not be used for worship:

• Fajr: app 05:12; mosque beginning 05:15; congregation 05:40.
• Dhuhr: app 12:08; mosque beginning 12:13; congregation 13:00.
• Asr: app 15:10; mosque first start 15:10; second start 15:48; congregation 16:00.
• Maghrib: app 17:25; mosque beginning 17:28; congregation 17:35.
• Isha: app 18:55; mosque beginning 19:05; congregation 19:30.

Reading only the congregation column would suggest five substantial disagreements. Comparing beginnings instead leaves much smaller differences, and the app’s Asr already matches one published start. The remaining entries still need explanation, but the comparison now shows which questions are worth asking.

The next step is not to add three minutes to everything. In this example, Dhuhr differs by five minutes and Isha by ten. A single correction would conceal, rather than explain, the pattern. Put an explicit question beside each remaining mismatch and work through the checks below.

Check the date and the actual location

Confirm the Gregorian day, month and year, including the heading of a downloaded annual timetable. An overnight screenshot may refer to yesterday, while an app has moved to today. The Adhan calculation library explicitly requires a Gregorian date and latitude/longitude: a city name without a date is not a reproducible comparison. Adhan documentation, initialization parameters

Inspect the place shown inside the prayer app, not just the city displayed in the phone’s weather widget. Ask whether the app is using a searched city, a saved home location or its current position. Check the country as well as the place name. If coordinates are available, copy them into the worksheet; do not guess that two similarly named locations are interchangeable.

Also establish the mosque timetable’s geographical scope. East London Mosque says its start times cover the region enclosed by the M25. Its explanation includes region-wide allowances for sunrise and Maghrib. That is a published regional timetable, not necessarily the same product as an unadjusted calculation for one street address. East London Mosque: calculation and coverage

If location access is the unresolved issue, investigate that separately. Apple allows location permissions to be managed for individual apps; permission to one app does not establish what another app can obtain. A correct device location is therefore not sufficient evidence of the prayer app’s selected input. Apple: privacy and Location Services

Check the clock before changing the calculation

Write down the time zone and daylight-saving status for the date under review. A roughly one-hour shift across the schedule is a reason to examine the clock first, not proof that the twilight method is wrong. Adhan’s documentation specifically warns developers that a device’s time zone need not match the calculation coordinates. Adhan: prayer-time output and time zones

Check the phone’s current clock against a dependable local reference, then ask which zone the app uses to display the chosen city’s times. Keep those two checks separate. Correcting a phone clock will not explain an app intentionally displaying a timetable in a different zone.

For iPhone, Apple’s troubleshooting guidance covers automatic date/time, internet connectivity and the system setting that uses location to determine the time zone. Availability can depend on device restrictions, carrier and region. Consult the current instructions rather than assuming a toggle alone proves the clock is correct. Apple: date and time troubleshooting

Do not compensate for a clock problem by applying an offset to each prayer. First fix or clarify the clock input, then repeat the comparison with the original prayer settings.

Identify the method, including overrides

Record the full calculation-method name, not just “automatic” or “recommended.” Ask the mosque whether its times come from a published regional schedule, a calculation service or another documented process. Ask the app provider whether the named option imports that timetable or calculates its own times.

Software documentation shows why the distinction matters. Adhan has separate parameters for Fajr and Isha, an alternative Isha interval, an Asr convention, high-latitude handling and per-prayer adjustments. A preset name is not a complete record if those parameters have been changed. Adhan calculation parameters

If only Fajr and Isha differ, ask about their conventions and any seasonal policy. If the disagreement appears only during part of the year, send examples from both affected and unaffected dates. That pattern is evidence to take to the timetable’s publisher, not permission to select whichever option makes the evening easiest.

Treat an Asr difference as its own question

In the invented comparison, 15:10 and 15:48 are labelled as different Asr starts. The app matches the first; the congregation follows later. The useful question is which convention the reader follows, not which device is more precise.

Real timetables can identify these entries explicitly. East London Mosque labels its two columns “1 Mithl” and “2 Mithl.” Check that heading before treating the later number as a correction to the earlier one. The religious explanation of the shadow-length conventions belongs in a separate Asr discussion; here the task is to identify the setting and obtain appropriate guidance. East London Mosque timetable

Look for documented adjustments and rounding

Minute-level differences deserve documentation rather than improvisation. PrayTimes supports individual offsets and different rounding choices. This establishes that these mechanisms exist in prayer software, not that your particular app uses that library or exposes every option. PrayTimes manual: tuning and rounding

There are also explicit timetable allowances. East London Mosque describes adding five minutes to its source’s solar-noon time for Dhuhr and three minutes to sunset for Maghrib. These published choices explain why a raw astronomical event and a mosque entry need not be identical. They are not offsets to copy indiscriminately elsewhere. East London Mosque: prayer times explained

Nor should a displayed minute be mistaken for unlimited observational precision. The U.S. Naval Observatory explains that atmospheric refraction, local topography and observer height affect observed rise and set times. Its astronomical explanation does not choose a religious timetable, but it cautions against treating small numerical differences as automatic evidence of incompetence. USNO: rise/set accuracy

Send a question someone can answer

A useful enquiry might read: “For this date and location, I am comparing your beginning times with this app. These are the time zone, method, Asr convention and adjustments shown. Fajr differs by three minutes and Isha by ten; the other differences are listed below. Does your timetable use published allowances or a seasonal method?” Attach the relevant original timetable link.

If displayed times agree but the alert arrives late, stop changing calculation settings: the remaining issue concerns the notification rather than the timetable. Record the displayed time and actual alert time separately.

Keep the explanation you receive with your settings. The goal is not to make two screens match at any cost. It is to understand what you follow, why a difference exists and whom to ask when it cannot be explained.

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Related reading: Why prayer times differ. Northern-summer prayer times. Privacy in Islamic apps.