Lunar Calendar Converter
Convert any date between six major world calendar systems — Gregorian, Islamic Hijri, Hebrew, Chinese, Ethiopian, and Hindu Vikram Samvat — instantly and accurately. Includes a live moon phase display for any selected date. All calculations run locally in your browser with no data sent to any server.
Converted Dates
Common Era (CE)
Anno Hegirae (AH) — lunar calendar
Anno Mundi (AM) — lunisolar
Traditional lunisolar calendar
Ethiopian Era (EE) — solar calendar
Vikram Samvat (VS) — lunisolar
Moon phase is an approximation based on the mean synodic period of 29.53 days.
Why Use Our Lunar Calendar Converter?
Convert any date across Gregorian, Islamic Hijri, Hebrew, Chinese, and Ethiopian calendars simultaneously, plus Hindu Vikram Samvat — all in one tool.
Instantly see the lunar phase for any selected date — New Moon, Full Moon, quarters, and crescents — with illumination percentage and synodic cycle position.
All calendar conversions run entirely in your browser using pure mathematical algorithms. No data is ever sent to external servers.
Enter dates in Gregorian, Islamic Hijri, or Ethiopian format and all other calendars update instantaneously. Results can be copied in one click.
Common Use Cases for Lunar Calendar Converter
Find exact Gregorian equivalents of Islamic Eid, Jewish Rosh Hashanah, Ethiopian Timkat, or Hindu festivals that are announced in their native lunar or lunisolar calendar.
Cross-reference events recorded in ancient Arabic, Hebrew, or Ethiopian manuscripts with the modern Gregorian calendar — critical for historians, archaeologists, and researchers.
Convert Islamic AH dates from medieval texts, or match Chinese calendar years in genealogical research. Essential for academic papers requiring multi-calendar citations.
Schedule meetings or events that respect calendrical significance for colleagues or clients observing Islamic Hijri, Hebrew, or Hindu Vikram Samvat dates.
Ethiopia uses the Ethiopian Ge'ez calendar, which is 7–8 years behind the Gregorian calendar. Convert dates before booking local events, festivals, or appointments.
Explore how different civilizations structured time. The lunar calendar converter is an excellent educational tool for students studying world history and cultural studies.
Understanding Lunar Calendar Conversion
What is a Lunar Calendar Converter?
A lunar calendar converter translates dates between calendar systems that track time differently — some by the Moon's cycles (lunar), some by the Sun (solar), and some by both (lunisolar). Unlike the Gregorian calendar which divides the year into 12 fixed-length months based on Earth's orbit around the Sun, lunar calendars like the Islamic Hijri count months by the Moon's synodic cycle of approximately 29.5 days, resulting in a year of only 354 days. Our lunar calendar converter handles all five major world calendar systems using mathematically precise algorithms derived from the Julian Day Number (JDN) as a universal pivot point.
How Our Lunar Calendar Converter Works
- Input Your Date: Enter a date in any supported calendar — Gregorian, Islamic Hijri, or Ethiopian. The lunar calendar converter accepts all three formats as valid input calendars.
- Julian Day Number Pivot: The converter first transforms your date into a Julian Day Number (JDN), a continuous count of days since January 1, 4713 BCE. This universal astronomical standard enables lossless transformation between any pair of calendar systems.
- Simultaneous Output: From the JDN, the tool computes equivalent dates in all six calendar systems in parallel and displays them instantly. The moon phase for the selected date is also derived from the JDN using the mean synodic period.
The Five Calendar Systems Explained
- Islamic Hijri (AH): A pure lunar calendar of 12 synodic months totaling ~354 days per year. It begins from the Prophet Muhammad's migration (Hijra) from Mecca to Medina in 622 CE. Because it is shorter than the solar year, Islamic dates drift through all seasons over ~33 years.
- Hebrew (AM): A lunisolar calendar counting from the traditional date of Creation (Anno Mundi). It adds a 13th leap month (Adar I) in 7 of every 19 years (the Metonic cycle) to stay synchronized with both the Moon and the Sun.
- Chinese: A traditional lunisolar calendar organized in 60-year cycles using Heavenly Stems and Earthly Branches (生肖). Leap months are inserted irregularly to maintain solar alignment.
- Ethiopian (EE): A solar calendar derived from the Coptic calendar with 12 months of 30 days each plus a 13th short month (Pagume) of 5–6 days. It runs approximately 7–8 years behind the Gregorian calendar.
- Hindu Vikram Samvat (VS): A lunisolar calendar approximately 56–57 years ahead of the Gregorian calendar. Months are named after the 12 Nakshatras (lunar mansions) and divided into Shukla Paksha (waxing fortnight) and Krishna Paksha (waning fortnight).
Accuracy and Limitations
The Islamic Hijri conversion uses the standard tabular (civil) calculation, which may differ by ±1 day from actual moon sighting-based dates observed in specific regions. The Hebrew calendar algorithm implements the Molad system with standard postponement rules (Dehiyyot), matching the arithmetic Hebrew calendar used globally. The Chinese calendar conversion is an approximation based on the 60-year cycle. For ceremonial or religious purposes, always verify converted dates with authoritative local sources.
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What is a lunar calendar converter?
A lunar calendar converter is a tool that translates dates between different world calendar systems — including those based on the Moon's cycle (lunar), the Sun's cycle (solar), or both (lunisolar). Our lunar calendar converter supports six major calendars: Gregorian, Islamic Hijri, Hebrew, Chinese, Ethiopian, and Hindu Vikram Samvat.
How accurate is the Islamic Hijri conversion?
Our lunar calendar converter uses the standard tabular (arithmetic) Islamic calendar algorithm, which is accurate for civil and administrative purposes. However, some Muslim communities determine months by actual moon sighting (Ruʾyat al-hilāl), which can differ by ±1 day from the calculated result. For religious observances, always verify with your local authority.
Why is the Ethiopian date 7–8 years behind Gregorian?
The Ethiopian Orthodox calendar is derived from the ancient Coptic calendar and uses a different epoch for counting years. It calculates the birth of Christ approximately 7–8 years later than the Western Gregorian calendar does, resulting in the current Ethiopian year being 7 or 8 behind the Gregorian year depending on the time of year.
What is the Julian Day Number (JDN) used for?
The Julian Day Number is a continuous astronomical count of days since January 1, 4713 BCE (Julian calendar). The lunar calendar converter uses it as a universal pivot: every input date is first converted to its JDN, then from the JDN to all other calendars. This ensures mathematically consistent conversions across all calendar systems.
What are Shukla Paksha and Krishna Paksha in the Hindu calendar?
In the Hindu lunisolar calendar, each month is divided into two fortnights (Paksha). Shukla Paksha is the bright fortnight (days 1–15, waxing moon from New Moon to Full Moon). Krishna Paksha is the dark fortnight (days 16–30, waning moon from Full Moon back to New Moon). Many Hindu festivals are scheduled using these paksha designations.
Is my date data sent to a server when I use this tool?
No. The lunar calendar converter runs entirely in your browser using JavaScript. All calendar algorithm calculations are performed locally on your device. No data is transmitted to any server, ensuring complete privacy.
How does the moon phase calculation work?
The moon phase is calculated using the known Julian Day Number of a reference New Moon (January 6, 2000 CE) and the mean synodic period of 29.530588853 days. The tool computes how many days have elapsed since the reference New Moon and determines the current phase. This is an astronomical approximation and may vary by a few hours from the exact astronomical moment.
What is the Hebrew calendar's Metonic cycle?
The Hebrew calendar uses the Metonic cycle, discovered by the Greek astronomer Meton around 432 BCE, which observes that 235 lunar months nearly equal 19 solar years. To keep the Hebrew calendar synchronized with both the Moon and the seasons, a 13th leap month (Adar I) is added in years 3, 6, 8, 11, 14, 17, and 19 of each 19-year Metonic cycle.
Is the lunar calendar converter completely free?
Yes. The lunar calendar converter is 100% free with no usage limits, no account required, no premium tiers, and no hidden charges. All six calendar conversions plus moon phase display are available to everyone at no cost.