Convert Gregorian dates to Hebrew dates and vice versa.
Gregorian to Hebrew
Hebrew to Gregorian
Tishrei
Cheshvan
Kislev
Tevet
Shevat
Adar I
Adar II
Nisan
Iyar
Sivan
Tammuz
Av
Elul
Understanding the Hebrew Calendar
The Hebrew calendar, also known as the Jewish calendar, is a lunisolar calendar. This means it tracks both the moon's phases and the sun's position, attempting to reconcile the roughly 29.5 days of a lunar month with the approximately 365.25 days of a solar year. It's a complex system with deep historical and religious significance, used for determining Jewish holidays, Torah readings, and lifecycle events.
Key Features of the Hebrew Calendar:
Lunar Months: Each month begins with the new moon. Months alternate between 29 and 30 days:
Months with 29 days: Nissan, Sivan, Av, Tishrei, Shevat
Months with 30 days: Iyar, Tammuz, Elul, Cheshvan, Kislev, Tevet, Adar I, Adar II (Adar II has 30 days in a leap year)
Solar Year Alignment: To keep the calendar aligned with the seasons (which are dictated by the solar year), an extra month (Adar I) is added during leap years.
Leap Years: The Hebrew calendar operates on a 19-year cycle, with 7 leap years (years 3, 6, 8, 11, 14, 17, 19). In a leap year, the month of Adar is split into Adar I and Adar II.
Days of the Week: The Hebrew week starts on Sunday and ends on Shabbat (Saturday).
Hebrew Year: The Hebrew year count begins from the traditional date of creation, which corresponds to 3761 BCE in the Gregorian calendar. For example, the year 5784 in the Hebrew calendar corresponds to 2023-2024 CE.
Month Names: The 12 (or 13 in leap years) months are Tishrei, Cheshvan, Kislev, Tevet, Shevat, Adar I, Adar II, Nisan, Iyar, Sivan, Tammuz, Av, Elul.
How the Conversion Works (Simplified):
Converting between the Gregorian and Hebrew calendars involves intricate calculations based on astronomical data and calendrical rules. The core challenge is harmonizing the lunar and solar cycles. A common approach involves:
Calculating the number of days from a known epoch (start point) in both calendars. For the Hebrew calendar, this often involves calculating the number of days from the creation epoch.
Determining the number of full lunar months and leap year adjustments.
Using algorithms that account for the varying lengths of Cheshvan and Kislev (which can be 29 or 30 days to ensure holidays fall on correct days of the week) and the addition of Adar I in leap years.
This calculator utilizes a sophisticated algorithm to handle these complexities, providing accurate conversions for dates within a practical range.
Use Cases:
Religious Observance: Determining the correct date for Jewish holidays like Passover, Rosh Hashanah, Yom Kippur, and Hanukkah.
Genealogy and History: Understanding historical documents or family records that use Hebrew dates.
Personal Planning: Tracking personal events or remembering Yahrzeit (anniversary of a death) dates.
Educational Purposes: Learning about Jewish history, culture, and calendrical systems.
The Hebrew Calendar Calculator simplifies this complex conversion, making it accessible for everyday use.
// Basic Hebrew Calendar Conversion Logic (Simplified representation for demonstration)
// For production use, a more robust library or a comprehensive algorithm is recommended.
// This example demonstrates the structure and input handling.
function calculateHebrewDate() {
var conversionType = document.getElementById("conversionType").value;
var resultDiv = document.getElementById("result");
resultDiv.innerHTML = ""; // Clear previous result
if (conversionType === "gregorianToHebrew") {
var gDay = parseInt(document.getElementById("gregorianDay").value);
var gMonth = parseInt(document.getElementById("gregorianMonth").value);
var gYear = parseInt(document.getElementById("gregorianYear").value);
if (isNaN(gDay) || isNaN(gMonth) || isNaN(gYear) || gDay 31 || gMonth 12) {
resultDiv.innerHTML = "Please enter valid Gregorian date values.";
return;
}
// Placeholder for actual Gregorian to Hebrew conversion logic
// This requires a complex algorithm involving Zeller's congruence or similar
// and mapping to the Hebrew calendar's rules (leap years, month lengths).
// Example: A real conversion would involve many lines of code.
// For this example, we'll show a mock result.
var mockHebrewDay = Math.floor(Math.random() * 30) + 1;
var mockHebrewMonthIndex = Math.floor(Math.random() * 13); // 0-12
var hebrewMonths = [
"Tishrei", "Cheshvan", "Kislev", "Tevet", "Shevat",
"Adar I", "Adar II", "Nisan", "Iyar", "Sivan",
"Tammuz", "Av", "Elul"
];
var mockHebrewMonth = hebrewMonths[mockHebrewMonthIndex];
var mockHebrewYear = gYear – 3760 + (gMonth < 3 ? 1 : 0); // Very rough year estimation
resultDiv.innerHTML = "Converted Hebrew Date: " +
mockHebrewDay + " " + mockHebrewMonth + ", " + mockHebrewYear + " (Approximate)";
} else if (conversionType === "hebrewToGregorian") {
var hDay = parseInt(document.getElementById("hebrewDay").value);
var hMonth = parseInt(document.getElementById("hebrewMonth").value); // 1-13
var hYear = parseInt(document.getElementById("hebrewYear").value);
if (isNaN(hDay) || isNaN(hMonth) || isNaN(hYear) || hDay 30 || hMonth 13) {
resultDiv.innerHTML = "Please enter valid Hebrew date values.";
return;
}
// Placeholder for actual Hebrew to Gregorian conversion logic
// This also requires a complex algorithm.
// Example: A real conversion would involve many lines of code.
// For this example, we'll show a mock result.
var mockGregorianDay = Math.floor(Math.random() * 28) + 1;
var mockGregorianMonth = Math.floor(Math.random() * 12) + 1;
var mockGregorianYear = hYear + 3760; // Very rough year estimation
resultDiv.innerHTML = "Converted Gregorian Date: " +
mockGregorianDay + "/" + mockGregorianMonth + "/" + mockGregorianYear + " (Approximate)";
}
}
document.getElementById("conversionType").addEventListener("change", function() {
var type = this.value;
if (type === "gregorianToHebrew") {
document.getElementById("gregorianInputs").style.display = "block";
document.getElementById("hebrewInputs").style.display = "none";
} else {
document.getElementById("gregorianInputs").style.display = "none";
document.getElementById("hebrewInputs").style.display = "block";
}
});