kb除以1024,mb除以1024^2,GB除以1024^3。就这么简单。

这是Chris Jester-Young的实现，我见过的最干净的，结合了php。net的和一个精度参数。

function formatBytes($size, $precision = 2)
{
    $base = log($size, 1024);
    $suffixes = array('', 'K', 'M', 'G', 'T');   

    return round(pow(1024, $base - floor($base)), $precision) .' '. $suffixes[floor($base)];
}

echo formatBytes(24962496);
// 23.81M

echo formatBytes(24962496, 0);
// 24M

echo formatBytes(24962496, 4);
// 23.8061M

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');

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]);
}

function byte_format($size) {
    $bytes = array( ' KB', ' MB', ' GB', ' TB' );
    foreach ($bytes as $val) {
        if (1024 <= $size) {
            $size = $size / 1024;
            continue;
        }
        break;
    }
    return round( $size, 1 ) . $val;
}

这是我的选择，简短明了:

/**
 * @param int $bytes Number of bytes (eg. 25907)
 * @param int $precision [optional] Number of digits after the decimal point (eg. 1)
 * @return string Value converted with unit (eg. 25.3KB)
 */
function formatBytes($bytes, $precision = 2) {
    $unit = ["B", "KB", "MB", "GB"];
    $exp = floor(log($bytes, 1024)) | 0;
    return round($bytes / (pow(1024, $exp)), $precision).$unit[$exp];
}

或者，更愚蠢和有效:

function formatBytes($bytes, $precision = 2) {
    if ($bytes > pow(1024,3)) return round($bytes / pow(1024,3), $precision)."GB";
    else if ($bytes > pow(1024,2)) return round($bytes / pow(1024,2), $precision)."MB";
    else if ($bytes > 1024) return round($bytes / 1024, $precision)."KB";
    else return ($bytes)."B";
}