Excel date conversion using PHP Excel
Please use this formula to change from Excel date to Unix date, then you can use "gmdate" to get the real date in PHP:
UNIX_DATE = (EXCEL_DATE - 25569) * 86400
and to convert from Unix date to Excel date, use this formula:
EXCEL_DATE = 25569 + (UNIX_DATE / 86400)
After putting this formula into a variable, you can get the real date in PHP using this example:
$UNIX_DATE = ($EXCEL_DATE - 25569) * 86400;
echo gmdate("d-m-Y H:i:s", $UNIX_DATE);
When using PHPExcel you can use the built in function:
$excelDate = $cell->getValue(); // gives you a number like 44444, which is days since 1900
$stringDate = \PHPExcel_Style_NumberFormat::toFormattedString($excelDate, 'YYYY-MM-DD');