我自己的实现，从整数大小获得格式化文件大小。简单易懂，易于扩展，以适应更大的文件-只需遵循模式。

<?php

function getFormattedFileSize($size, $precision) 
{
    switch (true) 
    {
        case ($size/1024 < 1):
            return $size.'B';
        case ($size/pow(1024, 2) < 1):
            return round($size/1024, $precision).'KB';
        case ($size/pow(1024, 3) < 1):
            return round($size/pow(1024, 2), $precision).'MB';
        case ($size/pow(1024, 4) < 1):
            return round($size/pow(1024, 3), $precision).'GB';
        case ($size/pow(1024, 5) < 1):
            return round($size/pow(1024, 4), $precision).'TB';
        default:
            return 'Error: invalid input or file is too large.';
    }
}

function changeType($size, $type, $end){
    $arr = ['B', 'KB', 'MB', 'GB', 'TB'];
    $tSayi = array_search($type, $arr);
    $eSayi = array_search($end, $arr);
    $pow = $eSayi - $tSayi;
    return $size * pow(1024 * $pow) . ' ' . $end;
}

echo changeType(500, 'B', 'KB');

function formatBytes($bytes, $precision = 2) { 
    $units = array('B', 'KB', 'MB', 'GB', 'TB'); 

    $bytes = max($bytes, 0); 
    $pow = floor(($bytes ? log($bytes) : 0) / log(1024)); 
    $pow = min($pow, count($units) - 1); 

    // Uncomment one of the following alternatives
    // $bytes /= pow(1024, $pow);
    // $bytes /= (1 << (10 * $pow)); 

    return round($bytes, $precision) . ' ' . $units[$pow]; 
} 

(摘自php.net，有很多其他的例子，但我最喜欢这个:-)

我开发了自己的功能，将人类可读的内存大小转换为不同的大小。

function convertMemorySize($strval, string $to_unit = 'b')
{
    $strval    = strtolower(str_replace(' ', '', $strval));
    $val       = floatval($strval);
    $to_unit   = strtolower(trim($to_unit))[0];
    $from_unit = str_replace($val, '', $strval);
    $from_unit = empty($from_unit) ? 'b' : trim($from_unit)[0];
    $units     = 'kmgtph';  // (k)ilobyte, (m)egabyte, (g)igabyte and so on...


    // Convert to bytes
    if ($from_unit !== 'b')
        $val *= 1024 ** (strpos($units, $from_unit) + 1);


    // Convert to unit
    if ($to_unit !== 'b')
        $val /= 1024 ** (strpos($units, $to_unit) + 1);


    return $val;
}


convertMemorySize('1024Kb', 'Mb');  // 1
convertMemorySize('1024', 'k')      // 1
convertMemorySize('5.2Mb', 'b')     // 5452595.2
convertMemorySize('10 kilobytes', 'bytes') // 10240
convertMemorySize(2048, 'k')        // By default convert from bytes, result is 2

这个函数接受任何内存大小的缩写，比如“Megabyte, MB, MB, MB, m, kilobyte, K, KB, b, Terabyte, T....”，所以它是拼写安全的。

这是Kohana的实现，你可以使用它:

public static function bytes($bytes, $force_unit = NULL, $format = NULL, $si = TRUE)
{
    // Format string
    $format = ($format === NULL) ? '%01.2f %s' : (string) $format;

    // IEC prefixes (binary)
    if ($si == FALSE OR strpos($force_unit, 'i') !== FALSE)
    {
        $units = array('B', 'KiB', 'MiB', 'GiB', 'TiB', 'PiB');
        $mod   = 1024;
    }
    // SI prefixes (decimal)
    else
    {
        $units = array('B', 'kB', 'MB', 'GB', 'TB', 'PB');
        $mod   = 1000;
    }

    // Determine unit to use
    if (($power = array_search((string) $force_unit, $units)) === FALSE)
    {
        $power = ($bytes > 0) ? floor(log($bytes, $mod)) : 0;
    }

    return sprintf($format, $bytes / pow($mod, $power), $units[$power]);
}

试试这个;)

function bytesToSize($bytes) {
                $sizes = ['Bytes', 'KB', 'MB', 'GB', 'TB'];
                if ($bytes == 0) return 'n/a';
                $i = intval(floor(log($bytes) / log(1024)));
                if ($i == 0) return $bytes . ' ' . $sizes[$i]; 
                return round(($bytes / pow(1024, $i)),1,PHP_ROUND_HALF_UP). ' ' . $sizes[$i];
            }
echo bytesToSize(10000050300);