How to show file size of featured image? [duplicate]

Following function calculate file size, just you need change ‘/myfile/image.jpg’ with your featured image variable.

   <?php 
    function file_size($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; 
    }


    $feat_image = wp_get_attachment_url( get_post_thumbnail_id($post->ID) );

   //echo file_size('/myfile/image.jpg');
     echo file_size($feat_image);  
    ?>

And check out WP Codex