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# PHP jdtounix() Function [ PHP Calendar Reference](#) ## Example Convert a Gregorian calendar date to a Julian day count, then convert the Julian day count to a Unix timestamp: [Run Example »](#) * * * ## Definition and Usage The jdtounix() function converts a Julian day count to a Unix timestamp. **Note:** If the parameter _jd_ is not within the Unix epoch (meaning the Gregorian year must be between 1970 and 2037, or jd >= 2440588 and jd <= 2465342), the function will return false. The returned time is local time. **Tip:** See [unixtojd()](#) to convert a Unix timestamp to a Julian day count. ## Syntax jdtounix _(jd);_ | Parameter | Description | | :--- | :--- | | _jd_ | Required. A Julian day number between 2440588 and 2465342. | ## Technical Details | Return Value: | Returns the Unix timestamp for the start of the specified Julian day. | | :--- | | PHP Version: | 4+ | * * PHP Calendar Reference](#)