Methodology — How Every Time on This Site Is Calculated

Every time shown on this site is computed, not copied from a timetable. This page explains how, so you can judge how far to trust it and why it may differ from the timetable on your mosque wall.

The Ramadan date

Ramadan 1448 AH is projected to begin on 8 February 2027, following the astronomical calculation used by the Umm al-Qura calendar. This is an expected date. Islamic months begin with the sighting of the crescent after sunset on the 29th, so the actual start is decided on the evening of 29 Sha’ban and can fall a day either side of the projection.

The month is either 29 or 30 days. Nothing on this site states the number of fasts as a settled fact, because it is not knowable in advance.

Moon-sighting uncertainty

Countries apply different criteria: some accept an astronomical conjunction, some require a naked-eye report, some accept only sightings within their own territory, and some follow another country’s announcement. The crescent is genuinely easier to see further west on any given evening, so a one-day difference between neighbouring countries is normal rather than an error. Where this site shows a country-specific date, it reflects that country’s usual practice — not a guarantee.

Prayer-time calculation

Prayer times are derived from the sun’s position for a given latitude, longitude and date, using standard solar-position geometry:

• Fajr — when the sun reaches a set angle below the horizon before sunrise. The angle depends on the convention chosen.
• Sunrise and Maghrib — the geometric rising and setting of the sun’s upper limb, adjusted for atmospheric refraction and for the observer’s elevation where that is known.
• Dhuhr — solar noon, when the sun crosses the local meridian, with a short margin added.
• Asr — when an object’s shadow reaches a set multiple of its own length plus the shadow at noon. The standard convention uses one times; the Hanafi convention uses two. Both are used by large numbers of Muslims; neither is presented here as the correct one.
• Isha — when the sun reaches a set angle below the horizon after sunset, or a fixed interval after Maghrib in conventions that use one.

Calculation methods

The Fajr and Isha angles are the main source of difference between one timetable and another. This site selects a default convention per country based on what is commonly used there, and where a tool allows it you can change the method yourself. Changing the method changes Fajr and Isha noticeably, Asr only if you switch conventions, and sunrise, Dhuhr and Maghrib barely at all.

No convention is universally correct. Local religious authorities and individual mosques often apply their own settings, and many add a safety margin of a few minutes to Fajr or hold Iftar slightly after the computed sunset. That is why a difference of a few minutes between this site and your mosque is expected and is not evidence that either is wrong.

Sehri and Iftar

Sehri (Suhoor) ends at the entry of Fajr, and Iftar begins at Maghrib. The site uses the computed Fajr and Maghrib times for your location. Some printed timetables also show an imsak time a few minutes before Fajr as a precaution; that is a margin, not the limit itself.

Fasting duration

The fasting duration for a day is the interval between that day’s Fajr and that day’s Maghrib for your location. It changes slightly from day to day through the month as the sun’s declination shifts, and it varies enormously by latitude — far more between two countries than between two calculation methods. At very high latitudes the geometric definitions break down for part of the year; where that happens the site says so rather than printing a number that has no meaning.

Time zones and daylight saving

Times are computed in UTC and then converted using the IANA time zone of the city, so daylight-saving transitions are handled by rule rather than by a fixed offset. Countdowns are computed against your own location’s zone, never against the server’s.

Location detection

Location is resolved in the least intrusive order that works:

1. A city you picked before, remembered in your own browser.
2. Your browser’s time zone, which needs no permission and identifies only the zone.
3. Precise coordinates from the browser Geolocation API — only after you explicitly ask for it, and only with your permission.
4. Manual city search, always available.

Coordinates are not sent to our servers. If you decline permission, the manual picker is offered instead and you are not asked again.

Countdowns

The Ramadan countdown runs to the projected first fast. Sehri and Iftar countdowns run to the next Fajr or Maghrib for your resolved location, recomputed on the client so they follow your clock and your zone. Because they are built on a projected date, they carry the same uncertainty as the date itself.

Calendar generation

A generated calendar is the day-by-day application of everything above: for each day of the projected month, the Fajr, sunrise, Dhuhr, Asr, Maghrib and Isha times for your coordinates, plus the fasting duration. A downloaded calendar states the location, the year, the time zone and the calculation method it was produced with, so it can be checked later.

Known limits

• Dates are projections until a sighting confirms them.
• City coordinates are a single representative point; a large metropolitan area has real variation across it, usually under a minute or two.
• Elevation and local horizon obstruction are not modelled in detail.
• High-latitude locations need a convention for months when the sun does not reach the required angle, and any such convention is a choice rather than a computation.

If you find a time that looks wrong for your city, please tell us on the Corrections page.