File Size Calculator in PHP

Calculate the size of a file from a URL and display the size in respective units. This function takes a file url and calculates the size the file in php.

function calculateFileSize($url){
    $size = filesize($url);
    if($size>=1073741824) {
        $fileSize = round($size/1024/1024/1024,1).'GB';
    } elseif($size>=1048576) {
        $fileSize = round($size/1024/1024,1).'MB';
    } elseif($size>=1024) {
        $fileSize = round($size/1024,1).'KB';
    } else {
        $fileSize = $size.' bytes';
    }
    return $fileSize;
}