Why Prayer Time Websites Disagree
It's common to check two apps for the same city and see Fajr or Isha a few minutes apart. Almost always, this comes down to a handful of real, identifiable choices each site makes, not an error in either one.
Last updated
Four real reasons
Not an error, a different choice
Method
Different twilight angles for Fajr and Isha
Coordinates
One citywide point versus each suburb's own
Madhab
Hanafi versus Shafi'i Asr, 30 to 60 minutes apart
Freshness
Rounded or stale data versus a live daily calculation
Different calculation methods
Fajr and Isha are defined by a twilight angle. Different organisations have published different angles for the same twilight moment. One site defaulting to Muslim World League and another to ISNA or Umm al-Qura will show different Fajr and Isha times for the identical location and date, simply because they're applying different, both legitimate, angle conventions.
See the calculation method comparison for how wide that spread can be.
Different coordinates
A site that publishes one set of times for an entire metro area is using a single reference point, often the city centre, for every suburb. Sydney spans a wide area. A suburb at its edge can genuinely have Fajr or Maghrib a minute or two apart from the CBD.
A site calculating per suburb, using that suburb's own coordinates, will disagree with a single-point site even under the identical calculation method.
Different Asr madhab
A site defaulting to Hanafi Asr and another defaulting to Shafi'i will show Asr 30 to 60 minutes apart for the same city and day. The two conventions use a different shadow-length threshold entirely. See the Hanafi vs Shafi'i Asr guide for the full explanation.
Rounding and stale data
Some sites round to the nearest five minutes rather than showing the calculated minute exactly. Others publish a printed timetable for the whole month or year rather than recalculating daily. That can drift slightly from a live calculation as the month goes on.
Neither is necessarily wrong, but neither is directly comparable to a site that recalculates fresh every day either.
Nothing hidden
Transparency is the fix
Method, coordinates and madhab, all named
None of these differences are hidden if a site is upfront about the choices behind its own numbers.
This site's own method, stated plainly
A difference against another site can be traced to a specific, named cause rather than left as a mystery.
Frequently Asked Questions
If two sites disagree, does that mean one of them is wrong? +
Not necessarily. Dhuhr and Maghrib should match closely between accurate sites using the same coordinates, because they follow directly from the sun's position. Asr matches too when both sites use the same madhab. Fajr and Isha can legitimately differ because different calculation methods define them with different twilight angles.
Why would two sites disagree even for Dhuhr or Maghrib? +
Usually because they're using different coordinates. A site that shows one time for all of Sydney rather than calculating per suburb can be a minute or two off for suburbs far from wherever its single reference point sits.
How can I tell if a site's times are trustworthy? +
Check whether it names its calculation method and coordinates plainly. A site that's specific about its method, rather than just showing a number with no explanation, gives you something to actually verify against your own mosque or preference.