PHP convert KB MB GB TB etc to Bytes

Here's a function to achieve this:

function convertToBytes(string $from): ?int {
    $units = ['B', 'KB', 'MB', 'GB', 'TB', 'PB'];
    $number = substr($from, 0, -2);
    $suffix = strtoupper(substr($from,-2));

    //B or no suffix
    if(is_numeric(substr($suffix, 0, 1))) {
        return preg_replace('/[^\d]/', '', $from);
    }

    $exponent = array_flip($units)[$suffix] ?? null;
    if($exponent === null) {
        return null;
    }

    return $number * (1024 ** $exponent);
}

$testCases = ["13", "13B", "13KB", "10.5KB", "123Mi"];
var_dump(array_map('convertToBytes', $testCases));

Output:

array(5) { [0]=> int(13) [1]=> int(13) [2]=> int(13312) [3]=> int(10752) [4]=> NULL } int(1)

function toByteSize($p_sFormatted) {
    $aUnits = array('B'=>0, 'KB'=>1, 'MB'=>2, 'GB'=>3, 'TB'=>4, 'PB'=>5, 'EB'=>6, 'ZB'=>7, 'YB'=>8);
    $sUnit = strtoupper(trim(substr($p_sFormatted, -2)));
    if (intval($sUnit) !== 0) {
        $sUnit = 'B';
    }
    if (!in_array($sUnit, array_keys($aUnits))) {
        return false;
    }
    $iUnits = trim(substr($p_sFormatted, 0, strlen($p_sFormatted) - 2));
    if (!intval($iUnits) == $iUnits) {
        return false;
    }
    return $iUnits * pow(1024, $aUnits[$sUnit]);
}