The Julian Day Number (JDN) is a continuous count of days since the beginning of the Julian Period. This tool allows astronomers, historians, and developers to convert between Gregorian/Julian calendar dates and Julian Day Numbers accurately.
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Date to Julian Day Converter
Convert calendar dates to Julian Day Numbers (JDN) and vice versa. Essential for astronomy and historical chronology. Fast, free, and 100% private browser tool.
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About Date to Julian Day Converter
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1
Select Mode
Choose 'Date to Julian' or 'Julian to Date'.
2
Input Value
Enter the calendar date or the Julian Day Number.
3
Get Result
Instantly view the converted value.
Key Features
Bidirectional Conversion
Convert Date → JDN or JDN → Date.
Astronomy Ready
Precise calculations for astronomical applications.
Historical Accuracy
Supports historical dates and proleptic calendars.
Frequently Asked Questions
It is the integer number of days that have elapsed since the initial epoch at noon Universal Time (UT) Monday, January 1, 4713 BC.
It simplifies calculating the time interval between two events, as it avoids the complexities of months and leap years.
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