PhpSpreadsheet/tests/data/Shared/Date/ExcelToTimestamp1904.php

<?php

// Excel DateTimeStamp        Result            Comments
return [
    [1462, -1956528000],
    [1463, -1956441600],
    [22269, -158803200],
    [25569, 126316800],
    [30292, 534384000],
    [39611, 1339545600],
    [0.25, 21600], //  06:00:00
    [0.3333333333333333333, 28800], //  08:00.00
    [0.54321, 46933], //  02:57:46
];