Hijri Gregorian Calendar Converter
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Hijri & Gregorian Calendar Converter
Understanding the Hijri & Gregorian Calendar Converter
The Hijri calendar, also known as the Islamic calendar, is a lunar calendar used by Muslims worldwide to determine the proper days of Islamic holidays and rituals. It consists of 12 months and is based on the sighting of the moon. The Gregorian calendar, on the other hand, is a solar calendar widely used internationally. This converter allows for seamless conversion between these two important calendar systems.
How the Conversion Works (Simplified Overview)
Converting between the Hijri and Gregorian calendars is a complex astronomical calculation due to their different bases (lunar vs. solar) and varying month lengths. The Hijri year is approximately 10-12 days shorter than the Gregorian year. Accurate conversion requires sophisticated algorithms that account for leap years in both systems and the precise astronomical cycles.
Gregorian to Hijri Conversion:
This process involves determining the number of days elapsed since a known epoch (a reference point in time) for both calendars and then calculating the corresponding date in the target calendar. The converter uses established algorithms to approximate the Hijri date based on the provided Gregorian date.
Hijri to Gregorian Conversion:
Similarly, converting from Hijri to Gregorian involves using algorithms that map the Hijri date to its Gregorian equivalent. This often relies on astronomical calculations and historical data to ensure accuracy.
Use Cases for the Hijri Gregorian Calendar Converter:
- Islamic Practices: Muslims use the Hijri calendar for determining the start and end of Ramadan, the dates of Eid al-Fitr and Eid al-Adha, and other religious observances. This converter helps in planning these events when coordinating with the Gregorian calendar.
- International Planning: Businesses and individuals operating globally often need to align schedules and events across different calendar systems. This tool facilitates such coordination.
- Historical Research: When studying historical documents or events, understanding dates in both calendars is crucial for accurate contextualization.
- Cultural Understanding: For those unfamiliar with the Hijri calendar, this tool provides an easy way to understand Islamic dates in a familiar Gregorian format, fostering better cultural exchange.
Important Notes:
- The accuracy of Hijri date predictions can vary slightly due to the observational nature of the Hijri calendar's start of the month (moon sighting). This converter typically uses a calculated astronomical approach for consistency.
- Leap years in the Gregorian calendar (adding an extra day to February) and the varying lengths of Hijri months (29 or 30 days) are factored into the conversion.
// JavaScript library for date conversions (simplified for this example)
// In a real-world scenario, you'd use a robust library like 'hijri-converter' or implement detailed algorithms.
// For demonstration, we'll use a basic approximation that might not be perfectly accurate for all dates.
// A very basic lookup for month names (not used in conversion logic itself but for display if needed)
var hijriMonthNames = [
"Muharram", "Safar", "Rabi' al-Awwal", "Rabi' al-Thani", "Jumada al-Awwal", "Jumada al-Thani",
"Rajab", "Sha'ban", "Ramadan", "Shawwal", "Dhu al-Qi'dah", "Dhu al-Hijjah"
];
// — Conversion Logic —
// This is a highly simplified approximation. Real-world converters use complex algorithms.
// We'll simulate a basic conversion based on a known difference in days per year.
var GREGORIAN_EPOCH_OFFSET = Date.UTC(1600, 0, 1); // January 1, 1600 Gregorian
var HIJRI_EPOCH_OFFSET = -1948585; // Approximate Julian Day Number for 16 July 622 (start of Hijri Year 1)
function toJulianDay(gregorianYear, gregorianMonth, gregorianDay) {
// Simple approximation for Julian Day Number calculation
var date = new Date(Date.UTC(gregorianYear, gregorianMonth – 1, gregorianDay));
return Math.floor((date.getTime() / 86400000) + 2440587.5); // Convert milliseconds to days since JD 0
}
function fromJulianDay(julianDay) {
// Simple approximation to convert Julian Day Number back to Gregorian Date
var ms = (julianDay – 2440587.5) * 86400000;
var date = new Date(ms);
return {
year: date.getUTCFullYear(),
month: date.getUTCMonth() + 1,
day: date.getUTCDate()
};
}
// Approximation for converting Gregorian to Hijri
function gregorianToHijri(gregorianYear, gregorianMonth, gregorianDay) {
var gregoryanJD = toJulianDay(gregorianYear, gregorianMonth, gregorianDay);
var daysDifference = gregoryanJD – HIJRI_EPOCH_OFFSET;
var hijriYear = Math.floor((daysDifference – 30) / 354.37); // Approximation of Hijri year
var remainingDays = daysDifference – (hijriYear – 1) * 354.37; // Days into the current Hijri year
var hijriMonth = 0;
var hijriDay = 0;
var daysInHijriMonth = 0;
for (var m = 1; m <= 12; m++) {
daysInHijriMonth = (m % 2 === 0) ? 29 : 30; // Approximate month lengths
if (m === 2 && hijriYear % 33 === 15) { // Approximate leap year for Feb in Hijri (simplification)
daysInHijriMonth = 30;
}
if (remainingDays <= daysInHijriMonth) {
hijriMonth = m;
hijriDay = Math.floor(remainingDays);
break;
}
remainingDays -= daysInHijriMonth;
}
// Adjust day if it's the last day of a 30-day month and calculation yielded 30
if (hijriDay === 30 && (hijriMonth % 2 === 1 || (hijriMonth === 2 && hijriYear % 33 === 15))) {
// This is a rough check; month lengths are complex.
}
// Basic validation and edge case adjustments for day and month
if (hijriDay === 0) hijriDay = 1;
if (hijriMonth === 0) {
hijriMonth = 1;
hijriDay = Math.max(1, hijriDay – 30); // Adjust if calculation bled into next year
}
return { year: hijriYear, month: hijriMonth, day: hijriDay };
}
// Approximation for converting Hijri to Gregorian
function hijriToGregorian(hijriYear, hijriMonth, hijriDay) {
var daysInHijriYear = 354;
if (hijriYear % 33 === 15 || hijriYear % 33 === 16 || hijriYear % 33 === 17) {
daysInHijriYear = 355; // Approximation for leap years in Hijri cycle
}
var daysIntoHijriYear = 0;
for (var m = 1; m < hijriMonth; m++) {
daysIntoHijriYear += (m % 2 === 0) ? 29 : 30; // Approximate month lengths
if (m === 2 && hijriYear % 33 === 15) { // Approximate leap year for Feb in Hijri
daysIntoHijriYear += 1;
}
}
daysIntoHijriYear += hijriDay;
var approximateJulianDay = HIJRI_EPOCH_OFFSET + (hijriYear – 1) * 354.37 + daysIntoHijriYear; // Use fractional year for better average
return fromJulianDay(approximateJulianDay);
}
function convertToHijri() {
var gregorianDay = parseInt(document.getElementById("gregorianDay").value);
var gregorianMonth = parseInt(document.getElementById("gregorianMonth").value);
var gregorianYear = parseInt(document.getElementById("gregorianYear").value);
var resultDisplay = document.querySelector("#resultToHijri .result-display");
resultDisplay.textContent = "-";
resultDisplay.classList.remove("error-message");
if (isNaN(gregorianDay) || isNaN(gregorianMonth) || isNaN(gregorianYear) ||
gregorianDay 31 || gregorianMonth 12 || gregorianYear daysInMonth[gregorianMonth]) {
resultDisplay.textContent = "Invalid day for the selected Gregorian month and year.";
resultDisplay.classList.add("error-message");
return;
}
try {
var hijriDate = gregorianToHijri(gregorianYear, gregorianMonth, gregorianDay);
var displayString = hijriDate.day + " " + hijriMonthNames[hijriDate.month – 1] + ", " + hijriDate.year + " AH";
resultDisplay.textContent = displayString;
} catch (e) {
console.error("Error during conversion:", e);
resultDisplay.textContent = "Conversion error. Please check inputs.";
resultDisplay.classList.add("error-message");
}
}
function convertToGregorian() {
var hijriDay = parseInt(document.getElementById("hijriDay").value);
var hijriMonth = parseInt(document.getElementById("hijriMonth").value);
var hijriYear = parseInt(document.getElementById("hijriYear").value);
var resultDisplay = document.querySelector("#resultToGregorian .result-display");
resultDisplay.textContent = "-";
resultDisplay.classList.remove("error-message");
if (isNaN(hijriDay) || isNaN(hijriMonth) || isNaN(hijriYear) ||
hijriDay 30 || hijriMonth 12 || hijriYear daysInHijriMonth) {
resultDisplay.textContent = "Invalid day for the selected Hijri month.";
resultDisplay.classList.add("error-message");
return;
}
try {
var gregorianDate = hijriToGregorian(hijriYear, hijriMonth, hijriDay);
var monthNames = ["January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"];
var displayString = monthNames[gregorianDate.month – 1] + " " + gregorianDate.day + ", " + gregorianDate.year + " AD";
resultDisplay.textContent = displayString;
} catch (e) {
console.error("Error during conversion:", e);
resultDisplay.textContent = "Conversion error. Please check inputs.";
resultDisplay.classList.add("error-message");
}
}