In PHP Spreadsheet, the date or time values are stored in an excel sheet in the form of timestamp which is a floating point value. So in order to store date/time in a human-readable format, need to calculate the correct excel timestamp and finally set a number format mask.
Example:
| <?php  // PHP program to set a date time value in excel sheet require_once('vendor/autoload.php');  usePhpOffice\PhpSpreadsheet\Spreadsheet; usePhpOffice\PhpSpreadsheet\Writer\Xlsx;   // Creates New Spreadsheet $spreadsheet= newSpreadsheet();   // Retrieve the current active worksheet $sheet= $spreadsheet->getActiveSheet();    // Set the number format mask so that the excel timestamp  // will be displayed as a human-readable date/time $spreadsheet->getActiveSheet()->getStyle('A1')     ->getNumberFormat()     ->setFormatCode(     \PhpOffice\PhpSpreadsheet\Style\NumberFormat::FORMAT_DATE_DATETIME     );   // Get current date and timestamp // Convert to an Excel date/time $dateTime= time();  $excelDateValue= \PhpOffice\PhpSpreadsheet\Shared\Date::PHPToExcel(                   $dateTime);    // Set cell A1 with the Formatted date/time value $sheet->setCellValue('A1',$excelDateValue);   // Write an .xlsx file  $writer= newXlsx($spreadsheet);  // Save .xlsx file to the current directory $writer->save('gfgdate.xlsx'); ?>  | 
Output:
Reference: https://phpspreadsheet.readthedocs.io/en/develop/topics/accessing-cells/


 
                                    








