Umm al Qura Date Converter/ Islamic Date Converter – Gregorian Calendar Converter

The Bridge: Julian Day Number (JDN)

Different calendars have unique starting points and rules. To accurately convert between them, a neutral reference system called the Julian Day Number (JDN) is used. The JDN is a continuous count of days that have passed since a remote, fixed start date (January 1, 4713 BC).

The Conversion Process

1. First, the Gregorian date you enter is converted into its unique Julian Day Number.
2. The Umm al-Qura calendar also has a specific start date (epoch) which corresponds to a known Julian Day Number.
3. By calculating the difference in days from the Umm al-Qura epoch, we can find the exact corresponding Umm al-Qura date.

Reversing the Process

Converting from an Umm al Qura date to a Gregorian date uses the same logic in reverse. The Umm al-Qura date is used to find its Julian Day Number, which is then converted back into the familiar Gregorian calendar date.