What is a Julian date?
A Julian date is a date representation based on a continuous count of days, often used in astronomy and technical systems.
Date & Time
Julian Date Converter
Convert calendar dates to Julian dates directly in your browser. Calculate Julian day numbers and convert Julian dates back to standard calendar dates.
Tool
Julian Date Converter
Convert calendar dates to Julian dates directly in your browser. Calculate Julian day numbers and convert Julian dates back to standard calendar dates.
This tool runs in your browser. Your input is processed locally and is not uploaded.
About this Tool
Use this free Julian date converter to convert normal calendar dates into Julian date values and back. It is useful for astronomy, date systems, historical data, technical logs, and scientific references.
Conversion Formula
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Julian date conversion maps a calendar date to a continuous day count. Depending on the selected format, the result can be shown as a Julian day number or as a year plus day-of-year style value.
Examples
- Convert a calendar date such as 2026-06-29 to a Julian date
- Convert a Julian day number back to a readable calendar date
- Use Julian dates for astronomy, logs, or technical date references
Frequently Asked Questions
Is Julian date the same as day of year?
Not always. Some industries use “Julian date” to mean day of year, while astronomy uses Julian day numbers. The converter can explain and separate these formats.
Can I convert Julian dates back to calendar dates?
Yes. The converter can support conversion from Julian date values back to standard calendar dates.
Does this run locally?
Yes. The conversion can be performed directly in your browser without uploading date values to a server.
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