Date & Time Tools
Julian Date Converter
Convert between Gregorian calendar dates and Julian day numbers.
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What is Julian Date?
Julian day numbers count continuous days since noon on January 1, 4713 BC. This tool converts between those numbers and calendar dates, including the Modified Julian Date (MJD).
How it works
It implements the standard Gregorian↔Julian day algorithms (the Fliegel–Van Flandern / Richards formulas), validating both directions for round-trip accuracy.
- Enter your input. Type or paste your input into the field above — the tool responds instantly.
- Review the result. Output updates live as you type. Everything runs entirely in your browser.
- Copy or download. Use the Copy button to grab the result, or Download to save it as a file.
Examples
Realistic sample
Paste or type any realistic input — the tool computes the result locally and instantly.
Common mistakes
Expecting a server round-trip
Nothing is uploaded — every tool in this category runs entirely in your browser.