Hijri Date Converter
Calculate hijri date easily with our free tool. Get practical results, tips, and comparisons for everyday decisions. Get results you can export or share.
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The conversion uses Julian Day Numbers as an intermediate step. First, the Gregorian date is converted to a Julian Day Number using the standard astronomical formula. Then, the Julian Day Number is converted to the Hijri calendar using the tabular Islamic calendar algorithm, which accounts for the 30-year leap cycle of the lunar calendar.
Last reviewed: December 2025
Worked Examples
Example 1: Gregorian to Hijri Conversion
Example 2: Hijri to Gregorian Conversion
Background & Theory
The Hijri Date Converter 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 Hijri Date Converter 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
JD = floor(365.25 × (Y+4716)) + floor(30.6001 × (M+1)) + D + B − 1524.5 (Gregorian to Julian Day)
The conversion uses Julian Day Numbers as an intermediate step. First, the Gregorian date is converted to a Julian Day Number using the standard astronomical formula. Then, the Julian Day Number is converted to the Hijri calendar using the tabular Islamic calendar algorithm, which accounts for the 30-year leap cycle of the lunar calendar.
Worked Examples
Example 1: Gregorian to Hijri Conversion
Problem: Convert March 21, 2026 (Gregorian) to the Hijri calendar date.
Solution: Using the Julian Day Number algorithm:\n1. Calculate JD for March 21, 2026\n2. Convert JD to Hijri calendar\n3. Result: approximately 1 Ramadan 1447 AH\n(Note: actual date may vary by 1-2 days based on moon sighting)
Result: March 21, 2026 ≈ 1 Ramadan 1447 AH
Example 2: Hijri to Gregorian Conversion
Problem: Convert 10 Dhul Hijjah 1446 AH (Eid al-Adha) to Gregorian.
Solution: Using the reverse Julian Day Number algorithm:\n1. Calculate JD for 10 Dhul Hijjah 1446\n2. Convert JD to Gregorian calendar\n3. Result: approximately June 6, 2025
Result: 10 Dhul Hijjah 1446 AH ≈ June 6, 2025
Frequently Asked Questions
Why do Hijri dates sometimes differ between countries?
Hijri dates can differ between countries because the start of each Islamic month traditionally depends on the physical sighting of the new crescent moon (hilal) by reliable witnesses. Since the moon is visible at different times in different locations due to geographical position, weather conditions, and atmospheric clarity, one country may announce the start of a new month a day before or after another. Some countries use astronomical calculations to predict moon visibility, while others rely strictly on physical sighting. Saudi Arabia, for example, uses the Umm al-Qura calendar based on calculations, while many other countries still rely on local moon sighting committees.
How accurate is the mathematical Hijri-Gregorian conversion?
Mathematical conversion algorithms like the Tabular Islamic Calendar provide a systematic approximation but can differ from actual observed dates by one to two days. This is because the actual Islamic calendar is based on moon sighting rather than fixed mathematical rules. The tabular calendar uses an alternating pattern of 29 and 30 day months with a leap day added in specific years of a 30-year cycle (years 2, 5, 7, 10, 13, 16, 18, 21, 24, 26, 29). For historical dates, the margin of error may be larger. For precise religious observances, always refer to your local Islamic authority or mosque for confirmed dates.
How do I verify Hijri Date Converter'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.
How do I get the most accurate result?
Enter values as precisely as possible using the correct units for each field. Check that you have selected the right unit (e.g. kilograms vs pounds, meters vs feet) before calculating. Rounding inputs early can reduce output precision.
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.
Does Hijri Date Converter work offline?
Once the page is loaded, the calculation logic runs entirely in your browser. If you have already opened the page, most calculators will continue to work even if your internet connection is lost, since no server requests are needed for computation.
References
Reviewed by Daniel Agrici, Founder & Lead Developer · Editorial policy