Ramadan Calendar Calculator
Calculate ramadan calendar easily with our free tool. Get practical results, tips, and comparisons for everyday decisions.
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Adjust values & calculateRamadan Schedule Overview
Formula
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.
Last reviewed: December 2025
Worked Examples
Example 1: Fasting Schedule in Makkah (Day 1 of Ramadan)
Example 2: Fasting Schedule in London (Day 15 of Ramadan)
Background & Theory
The Ramadan Calendar Calculator applies the following established principles and formulas. Islamic financial and religious calculations operate within a framework that integrates theological principles with precise mathematical methodology. Zakat, one of the five pillars of Islam, requires payment of 2.5% of qualifying wealth held above the nisab threshold for a complete lunar year. The nisab is pegged to the value of 85 grams of gold or 595 grams of silver, whichever provides the lower threshold, and must be recalculated against current market prices. Qualifying wealth includes cash, savings, business inventory, and investment assets, but excludes primary residence, personal-use items, and tools of trade. Hijri calendar conversion is essential for determining Ramadan dates, Zakat anniversaries, and contract terms expressed in lunar months. The Hijri calendar contains 12 lunar months totalling approximately 354.37 days, making it roughly 11 days shorter than the Gregorian year. Converting between calendars requires accounting for the accumulated drift: since the Hijri epoch of 622 CE (the Prophet's migration from Mecca to Medina), the difference compounds annually. Qibla direction calculation employs spherical trigonometry to determine the great-circle bearing from any point on Earth toward the Kaaba in Mecca (coordinates 21.4225°N, 39.8262°E). The formula accounts for the curvature of the Earth, meaning the bearing from New York to Mecca is approximately northeast rather than the intuitive eastward direction seen on flat maps. Prayer times are determined by solar angles: Fajr begins when the sun is 15-18 degrees below the horizon before dawn; Dhuhr at solar noon; Asr when shadow length equals object height plus its shadow at noon; Maghrib at sunset; and Isha when twilight disappears. These calculations vary by latitude and season, requiring location-specific algorithms. Islamic finance prohibits riba (interest), requiring profit-sharing structures such as Mudarabah (capital provider and entrepreneur share profits at a pre-agreed ratio) and Musharakah (joint venture with proportional profit and loss sharing).
History
The history behind the Ramadan Calendar Calculator traces back through the following developments. Islamic civilisation made foundational contributions to mathematics and astronomy that underpin many of the calculation methods still used today. Muhammad ibn Musa al-Khwarizmi, working at the House of Wisdom in Baghdad in the 9th century, authored Al-Kitab al-mukhtasar fi hisab al-jabr wal-muqabala, the work from whose title the word algebra derives. His systematic approach to equation solving provided tools directly applicable to financial and calendar calculations. Al-Biruni in the 11th century developed sophisticated methods for calculating geographic coordinates and direction, including early formulations of what became the qibla calculation. The Hijri calendar was formally established by Caliph Umar ibn al-Khattab in 638 CE, fixing the Prophet Muhammad's migration (Hijra) from Mecca to Medina in 622 CE as the epoch. This calendar standardised religious observances across the expanding Muslim world. Islamic inheritance law (Faraid) was codified from Quranic verses and Hadith during the early Islamic period, establishing precise fractional shares for defined classes of heirs. The complexity of multi-heir scenarios drove development of sophisticated fraction arithmetic among early Islamic jurists and mathematicians. The Ottoman Empire administered Zakat as a state function for centuries, integrating it with broader fiscal policy until the empire's dissolution after World War I. The 20th century saw Islamic finance principles largely dormant in formal banking until the resurgence of Islamic banking in Egypt (Mit Ghamr Savings Bank, 1963) and the Gulf states following the 1973 oil boom provided capital for institution-building. The Accounting and Auditing Organization for Islamic Financial Institutions (AAOIFI), established in Bahrain in 1991, and the Islamic Financial Services Board (IFSB), established in Kuala Lumpur in 2002, created the standards infrastructure for modern Islamic finance. The global Islamic finance industry has grown to approximately three trillion US dollars in assets, spanning banking, takaful insurance, sukuk bonds, and Islamic funds across over 80 countries.
Key Features
- Calculate Zakat obligations on cash, savings, gold, silver, and business inventory by comparing total wealth against the nisab threshold and applying the 2.5% annual rate.
- Convert dates bidirectionally between Hijri (Islamic lunar) and Gregorian calendars, handling month boundary variations with both calculated and observed moon sighting options.
- Compute the Qibla direction (bearing) from any GPS coordinate to Mecca using great-circle calculations, with both compass bearing and map visualization.
- Calculate Islamic prayer times (Fajr, Dhuhr, Asr, Maghrib, Isha) for any location and date using sun angle methods from major juristic schools (Hanafi, Shafi'i, MWL, ISNA).
- Compute Mudarabah and Musharakah profit-sharing ratios between capital provider and working partner, with scenarios for different profit splits and loss allocation rules.
- Compare the effective cost of halal financing structures (Murabaha, Ijara, Diminishing Musharakah) against conventional interest-bearing loans for equivalent purchase amounts.
- Distribute an estate under Faraid Islamic inheritance law by entering heirs and their relationships, then calculating each heir's prescribed fractional share of the net estate.
- Estimate the likely start date of Ramadan and Eid al-Fitr by calculating the expected new lunar crescent visibility from a given location and historical sighting criteria.
Frequently Asked Questions
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.
How do I verify Ramadan Calendar Calculator's result independently?
The Formula section on this page shows the equation used. You can reproduce the calculation manually or in a spreadsheet using those steps. Compare your answer against the worked examples in the Examples section, which use known reference values so you can confirm the calculator is behaving as expected.
Why might my result differ from another tool or reference?
Differences typically arise from rounding conventions, the specific version of a formula (for example, simple vs compound interest), or unit inconsistencies between inputs. Check that both tools are using the same formula variant and the same units. The References section links to the authoritative source behind the formula used here.
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.
References
Reviewed by Daniel Agrici, Founder & Lead Developer · Editorial policy