Islamic Months Calculator
Convert between Hijri month names, numbers, and corresponding Gregorian date ranges. Enter values for instant results with step-by-step formulas.
Calculator
Adjust values & calculateGregorian Date
All Islamic Months
Formula
The conversion uses the Julian Day Number as an intermediary. Gregorian dates are first converted to JDN, then from JDN to Hijri dates using the tabular Islamic calendar algorithm. This mathematical approach tracks the 30-year Hijri cycle where 11 years have 355 days and 19 years have 354 days.
Last reviewed: December 2025
Worked Examples
Example 1: Convert Gregorian to Hijri Date
Example 2: Find Gregorian Date for Eid al-Adha 2025
Background & Theory
The Islamic Months 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 Islamic Months 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.
Frequently Asked Questions
Formula
Julian Day Number conversion between Hijri and Gregorian calendars
The conversion uses the Julian Day Number as an intermediary. Gregorian dates are first converted to JDN, then from JDN to Hijri dates using the tabular Islamic calendar algorithm. This mathematical approach tracks the 30-year Hijri cycle where 11 years have 355 days and 19 years have 354 days.
Worked Examples
Example 1: Convert Gregorian to Hijri Date
Problem: Convert March 25, 2025 to the Hijri calendar date.
Solution: Using the Julian Day Number conversion algorithm:\n1. Calculate Julian Day Number for March 25, 2025\n2. Apply the Hijri conversion formula\n3. The date falls in the month of Ramadan 1446 AH\nThe 25th of Ramadan is significant as it falls within the last ten nights when Laylat al-Qadr is sought.
Result: March 25, 2025 corresponds to approximately 25 Ramadan 1446 AH
Example 2: Find Gregorian Date for Eid al-Adha 2025
Problem: Determine the approximate Gregorian date for 10 Dhul Hijjah 1446 AH (Eid al-Adha).
Solution: Using the Hijri to Gregorian conversion:\n1. Input: 10 Dhul Hijjah 1446 AH\n2. Calculate the Julian Day Number from Hijri date\n3. Convert Julian Day to Gregorian calendar\nNote: Actual date may vary by 1-2 days based on moon sighting.
Result: 10 Dhul Hijjah 1446 AH falls approximately on June 6-7, 2025
Frequently Asked Questions
What are the twelve months of the Islamic (Hijri) calendar?
The twelve months of the Islamic calendar in order are: Muharram, Safar, Rabi al-Awwal, Rabi al-Thani, Jumada al-Ula, Jumada al-Thani, Rajab, Shaban, Ramadan, Shawwal, Dhul Qadah, and Dhul Hijjah. Each month begins with the sighting of the new crescent moon (hilal) and lasts either 29 or 30 days depending on the actual lunar cycle for that month. The Islamic year totals approximately 354 days, making it about 11 days shorter than the Gregorian solar year. This means Islamic months rotate through all Gregorian seasons over a cycle of approximately 33 years. Four of these months are considered sacred (haram): Muharram, Rajab, Dhul Qadah, and Dhul Hijjah, during which warfare was traditionally prohibited.
What is the significance of the four sacred months in Islam?
The four sacred months (Al-Ashhur al-Hurum) are Dhul Qadah, Dhul Hijjah, Muharram, and Rajab, as mentioned in the Quran in Surah At-Tawbah (9:36). Three of these months are consecutive (Dhul Qadah, Dhul Hijjah, and Muharram) while Rajab stands alone. During these months, fighting and warfare were prohibited in pre-Islamic Arabia, and this prohibition was upheld by Islam. The sacredness of these months has several practical and spiritual dimensions. Good deeds are considered more rewarding during these months, while sins are considered more severe. Dhul Qadah and Dhul Hijjah surround the Hajj pilgrimage, providing safe passage for pilgrims. Muharram includes the Day of Ashura (10th), and Rajab contains the Night Journey (Isra and Miraj) on the 27th.
How is the start of each Islamic month determined?
The start of each Islamic month is traditionally determined by the physical sighting of the new crescent moon (hilal) on the 29th evening of the current month. If the crescent is sighted, the new month begins the following day. If it is not sighted due to clouds, atmospheric conditions, or because the moon has not yet reached the visible crescent phase, the current month is completed at 30 days and the new month begins after that. This observational method means that the start date can vary by one day between different countries and regions. Some countries and organizations now use astronomical calculations to predict moon visibility, while others strictly adhere to physical sighting. Saudi Arabia uses the Umm al-Qura calendar for civil purposes but relies on official sighting committees for religious observances like Ramadan and Eid.
How do Islamic months relate to agricultural and seasonal activities?
Unlike solar calendars where months correspond to fixed seasons, Islamic months rotate through all seasons over approximately 33 years because the lunar year is shorter than the solar year. However, the original Arabic names of the months reflect the seasons during which they fell when the names were first assigned in pre-Islamic Arabia. Rabi al-Awwal and Rabi al-Thani mean First Spring and Second Spring, reflecting a springtime naming origin. Jumada al-Ula and Jumada al-Thani reference dry, parched land from a summer naming period. Ramadan derives from intense heat. This seasonal disconnection means that agricultural societies in the Muslim world typically use local solar calendars alongside the Hijri calendar for farming purposes, while reserving the Hijri calendar for religious observances and legal matters.
How accurate are the results from Islamic Months Calculator?
All calculations use established mathematical formulas and are performed with high-precision arithmetic. Results are accurate to the precision shown. For critical decisions in finance, medicine, or engineering, always verify results with a qualified professional.
Can I use the results for professional or academic purposes?
You may use the results for reference and educational purposes. For professional reports, academic papers, or critical decisions, we recommend verifying outputs against peer-reviewed sources or consulting a qualified expert in the relevant field.
References
Reviewed by Daniel Agrici, Founder & Lead Developer · Editorial policy