Ramadan Calendar Calculator
Calculate ramadan calendar easily with our free tool. Get practical results, tips, and comparisons for everyday decisions.
Formula
Fajr = Solar Noon − (1/15) × arccos[(sin(-18°) − sin(lat)sin(dec)) / (cos(lat)cos(dec))]
Prayer and fasting times are calculated using the sun's position. Fajr (dawn) occurs when the sun is 18° below the horizon. Maghrib (sunset) occurs at the geometric sunset. These depend on latitude, longitude, day of year, and the sun's declination.
Worked Examples
Example 1: Fasting Schedule in Makkah (Day 1 of Ramadan)
Problem: Calculate Suhoor and Iftar times for Makkah (lat 21.42°N, lng 39.83°E, UTC+3) on the first day of Ramadan.
Solution: Solar declination for ~March 18: ~-1.5°\nFajr angle: -18° below horizon\nFajr (Suhoor end): ~5:10 AM\nSunrise: ~6:15 AM\nMaghrib (Iftar): ~6:20 PM\nFast duration: ~13 hours 10 minutes
Result: Suhoor ends: ~5:00 AM | Iftar: ~6:22 PM | Fast: ~13h 10min
Example 2: Fasting Schedule in London (Day 15 of Ramadan)
Problem: Calculate fasting times for London (lat 51.51°N, lng -0.13°W, UTC+0) on day 15 of Ramadan (~early April).
Solution: Solar declination for ~April 1: ~4.5°\nFajr at 51.5°N latitude: ~4:30 AM\nSunrise: ~6:30 AM\nMaghrib: ~7:40 PM\nFast duration: ~15 hours 10 minutes\nNote: London fasting hours are longer due to higher latitude
Result: Suhoor ends: ~4:20 AM | Iftar: ~7:42 PM | Fast: ~15h 10min
Frequently Asked Questions
Why do fasting hours vary by location during Ramadan?
Fasting hours vary dramatically by location because they depend on geographic latitude. Near the equator, day length remains relatively constant at about 12 hours year-round, resulting in consistent fasting durations of approximately 12-13 hours. At higher latitudes, day length varies greatly with the seasons. When Ramadan falls in summer months at northern latitudes, fasting can last 18-20 hours (as in Scandinavia or northern Canada). Conversely, when Ramadan occurs in winter at these locations, fasting might only be 8-9 hours. Locations very close to the poles may experience perpetual daylight or darkness, in which case Islamic scholars generally advise following the times of the nearest city with distinguishable day and night, or following Makkah's times.
How does the Ramadan calendar shift each year?
Ramadan shifts approximately 10 to 11 days earlier each year on the Gregorian calendar because the Islamic calendar is a lunar calendar with 354 or 355 days per year, compared to the 365 or 366 days in the Gregorian solar calendar. This means Ramadan cycles through all seasons over approximately 33 years. In summer months, fasting hours are longer in the Northern Hemisphere, while in winter they are shorter. The exact start date of Ramadan is determined either by the physical sighting of the new crescent moon (hilal) or by astronomical calculations, depending on the methodology followed by different Muslim communities and countries. This is why the start date may differ by one or two days between regions.
What is the difference between business days and calendar days?
Calendar days include every day. Business days (or working days) exclude weekends (Saturday and Sunday) and public holidays. A 10-business-day deadline is typically 14 calendar days. Legal and financial deadlines often specify which type applies.
Can I share or bookmark my calculation?
You can bookmark the calculator page in your browser. Many calculators also display a shareable result summary you can copy. The page URL stays the same so returning to it will bring you back to the same tool.
What formula does Ramadan Calendar Calculator use?
The formula used is described in the Formula section on this page. It is based on widely accepted standards in the relevant field. If you need a specific reference or citation, the References section provides links to authoritative sources.
Is my data stored or sent to a server?
No. All calculations run entirely in your browser using JavaScript. No data you enter is ever transmitted to any server or stored anywhere. Your inputs remain completely private.