Why prayer times differ between apps and mosques

First compare the same kind of time

Start by asking whether both times are the same kind of time. Prayer timetables often have more than one column.

• Start time is when the prayer time begins. Timetables may label it begins, beginning or start. This is what our tool calculates.
• Congregation time (jamaah or iqamah) is when a mosque holds the prayer together. The mosque decides it.

Some mosques also list their own time for the call to prayer, separate from both. Read the column headings on the mosque’s own timetable before you compare.

Here is a hypothetical example. A calculated Dhuhr start of 13:00 and a congregation at 13:20 do not conflict, because they describe different events. The 20-minute gap is only an illustration. Each mosque sets its own gap, and Friday prayer schedules differ from one institution to the next.

Check the place, date and timezone

If most rows are off by roughly the same amount, check the inputs in this order:

1. Place. Confirm the country as well as the city, because some city names exist in several countries. A city preset uses an approximate centre point, which can differ from coordinates you or another app entered.
2. Date. Make sure both schedules show the same Gregorian date. In our tool, Today means today at the selected place. For a distant place, that may not be the date where you are.
3. Timezone. Confirm the zone name, such as America/Toronto or Europe/London. For a typed point or your device location, choose or confirm the zone yourself. Your device’s zone is only a convenience and may not be the zone at the point.

The size of the shift is a useful clue. About an hour points to a timezone or daylight-saving difference. About a day points to a different date, a point set to the wrong zone, or a time after midnight read without its next-day label. Use these as starting points for checking, not as definite answers.

Compare the effective method and Asr choice

When only some rows differ, the pattern tells you which setting to compare:

A common Canadian mismatch shows how this works. Our FCNA Canada profile uses 13° for Fajr and Isha, while the ISNA / North America profile uses 15°. The two are easy to confuse because the Canada profile starts from the same North America base. Their angles are different, so their Fajr and Isha times usually differ, although a night limit on a short summer night can bring them to the same minute. Services can also use the same method name for different presets or versions, so compare the numbers. To check each profile’s values, compare the calculation parameters.

The Moonsighting Committee (seasonal twilight) profile works differently from a fixed-angle profile. It follows the seasonal model in the Adhan 4.4.6 library. It first calculates geometric angle candidates for Fajr and Isha, then applies seasonal bounds that change through the year. A Moonsighting Committee row can therefore differ from a fixed-angle profile even when the degrees look similar. Another service’s option with the same name may use different built-in margins or solar formulas, so small gaps can remain. The profile name describes the calculation model. The profile is not set up for any particular mosque, and it doesn’t mean that any committee, mosque or religious body has endorsed our timetable.

Custom also lets Isha follow a different rule on dates you choose. Interval on selected dates uses a fixed interval of 30 to 180 whole minutes from the First date to the Last date. Cap on selected dates keeps the angle result but moves Isha earlier to the interval time on days when that time is earlier. Both modes use full Gregorian dates from 2020 to 2035, inclusive. A window can cross the new year, but it does not repeat in later years. Outside the window, Isha uses the selected angle and night rule, and Fajr uses its chosen angle and night rule at all times. Suppose two schedules match for part of the year and then separate on one date. In that case, compare their date windows before you compare their angles.

If only Asr differs, don’t add or subtract a fixed number of minutes to convert one rule into the other. Switch the Asr setting instead. Both rules measure from the noon shadow, and the gap between them changes with the date. The twilight type and the Isha settings don’t change Asr.

Check rounding and minute adjustments

Differences of one to a few minutes can come from adjustments, rounding or the solar calculation itself. Check these in order:

1. Reset your manual adjustments to zero and compare again.
2. Read the built-in adjustments. Several profiles add one minute to Dhuhr. The Moonsighting Committee profile adds 5 minutes to Dhuhr and 3 minutes to Maghrib, and you can still set manual minutes on each row. Calculation details lists built-in, manual and total minutes separately.
3. Check where an interval Isha starts. In the fixed-interval profiles, and in Custom with the default Unadjusted sunset origin, a Maghrib change doesn’t move Isha. In Custom with the Maghrib with adjustments origin, the interval counts from the adjusted Maghrib time. Changing Maghrib minutes then moves Isha on purpose. Isha’s own adjustment minutes are added last in both cases.
4. Allow for rounding. Times are rounded to the nearest minute. Two calculators using the same angles can still differ by a minute on some rows.
5. Allow for different solar formulas. Calculators use different formulas and approximations for the sun’s position. Even with identical settings, some rows can differ by a minute or two. On short summer nights the sun crosses the Fajr or Isha angle at a shallow slant. That makes those times more sensitive to small formula differences. When the settings are known to match, don’t treat a large gap, such as a quarter of an hour, as formula variation.
6. Look for safety margins. A mosque or issuing body may add its own precautionary minutes, or follow a maintained timetable rather than a plain angle calculation. Its published explanation will say so. A published mosque calendar records the times the mosque printed. The gap between that calendar and a calculated time is not an adjustment you can copy, unless the source states it.

Don’t add arbitrary minutes just to make two schedules agree. If you know the source’s actual adjustment, enter that value. A source may say that its Isha interval counts from its adjusted Maghrib. Only in that case should you set the Custom origin to Maghrib with adjustments. Otherwise, keep the default. A small remaining difference does not by itself show that the two schedules follow different conventions, or that either one is wrong. Ask the source which settings it uses before drawing a conclusion. If you know both sets of settings, they match, and the gap is still more than a minute or two, report the difference with those settings so it can be reproduced.

Check summer rules and next-day labels

Summer at higher latitudes can bring limit labels, unavailable rows and Isha times after midnight. Different situations sit behind them:

• Persistent twilight. The sun still sets and rises, but it doesn’t sink as far below the horizon as the selected Fajr or Isha angle requires. The ordinary night rule then supplies a limit. You can choose an angle-based share of the night (the angle divided by 60), the middle of the night, one-seventh or one-third. The night is measured from sunset on the timetable date to the next sunrise. Fajr’s limit counts back that same length from sunrise on the timetable date. The rule is a limit, not a replacement. When a valid angle time already falls inside the limit, the angle time stays. Limited rows are labelled Twilight rule limit. The rule doesn’t limit a fixed-interval Isha or an active date-window interval.
• Seasonal twilight. The Moonsighting Committee profile hides the ordinary night-rule setting and applies its own seasonal bounds. Rows using those bounds are labelled Seasonal twilight. At 55°N and above, the profile first uses a one-seventh-of-the-night candidate, as in Adhan 4.4.6, before its seasonal bounds, and the row label says so. In the southern hemisphere, the profile shifts its seasonal dates but does not use that northern one-seventh shortcut.
• Polar day or night. The sun does not set or does not rise at all. The night has no sunset or sunrise to be measured from, so the affected rows stay unavailable. A row can also be unavailable when the sun stays so close to the horizon that the calculator cannot resolve a time. A Custom cap does not create an Isha where the base calculation has none.

If two apps disagree in summer, compare their night rules and any limit labels first. If Isha appears at an early-morning hour, check its date badge. A late Isha after midnight belongs to the previous date’s timetable but falls on the next calendar day. A Custom date window also follows the timetable date, even when Isha falls after midnight. Rows labelled Date-window interval or Date-window cap show where a window is active. A month print shows the full window and policy, and each row shows its own criterion. A window may cover only part of the month, so read the row labels instead of assuming the whole month follows one rule. Our tool keeps missing values visible and never fills the gaps with midnight or another city’s times. Its next-prayer countdown pauses when a day is incomplete, and when two prayers fall in the same displayed minute.

Comparing with a published mosque calendar

On the prayer times page, a separate section below the calculator, Published mosque calendars, shows timetables as published by Al Rashid and Masjid Quba in Edmonton. It is a record of those sources, not a calculation profile, and it doesn’t tell you how either mosque prepares its times. The viewer keeps Adhaan and Sunrise times apart from Iqamah times. Its monthly table and CSV download show the source date for every row. Compare a calculated start with the mosque’s adhaan column, and treat iqamah as a congregation time.

The reviewed data covers 244 days: 1 June to 30 September 2026 for each mosque, 122 days each, captured on 31 October 2026 (UTC). The viewer always shows that coverage, the capture time and a link to the official source. You choose the mosque, a Gregorian date in Edmonton and the time format. The viewer opens on today’s date, so outside the covered range it shows no reviewed data. Select Open 15 July 2026 example to see a covered day. The viewer doesn’t reuse 2026 times for other years, fill gaps or substitute calculated values. It has no countdown, and it needs no location permission. Some published cells are held back instead of shown. For example, Masjid Quba’s Maghrib iqamah for 6 July 2026 is listed as 00:00, which falls outside the window before the next prayer. The viewer shows Check official timetable for that cell with no value, and the day’s 22:05 Maghrib adhaan stays. Rows that are out of range or held back stay unavailable, and the official source link still works.

The calculated rows show what the stated settings produce. They don’t reveal either mosque’s method. A calculated value close to a published one, such as 23:10 next to 23:14 and 23:13, is not evidence that a mosque uses that setting. The ISNA row shows how far a different method and night rule can move Isha, past midnight onto the next calendar day. These are dated historical examples, not current times. We don’t judge whether a mosque’s timetable is correct or whether a prayer is valid.

To understand summer and polar results, read the seasonal guide.

If the mismatch remains

If you have worked through these checks and still think our calculation is wrong, send enough detail for us to reproduce it:

• the city and country, or a point rounded to two decimal places (we don’t need your exact address)
• the Gregorian date and the timezone
• the profile name, or the Fajr and Isha angles or Isha interval
• the Asr choice, night rule and any manual adjustments
• the two values that differ, and where the other value came from

Then report a reproducible calculation issue.

For congregation times, ask the mosque directly. We can explain how a calculated time was produced. We don’t decide which convention is correct or rule on whether a prayer is valid.