Media library size Dashboard Widget

wp_library_size.php

<?php
add_action( 'wp_dashboard_setup', 'iv_wp_dashboard_setup' );

function iv_wp_dashboard_setup() {
	if( current_user_can( 'install_plugins' ) )
		wp_add_dashboard_widget( 'iv_folder_sizes', __( 'Folder Sizes' ), 'iv_wp_add_dashboard_widget' );
}

function iv_wp_add_dashboard_widget() {
	$upload_dir     = wp_upload_dir();
	$upload_space   = iv_foldersize( $upload_dir['basedir'] );
	$content_space  = iv_foldersize( WP_CONTENT_DIR );
	$wp_space       = iv_foldersize( ABSPATH );

	/* ABSOLUTE paths not being shown in Widget */
	echo '<i>Uploads</i>: ' . iv_format_size( $upload_space ) . '<br>';
	echo '<i>wp-content</i>: ' . iv_format_size( $content_space ) . '<br>';

	if( is_multisite() ) {
		echo '<i>wp-content/blogs.dir</i>: ' . iv_format_size( iv_foldersize( WP_CONTENT_DIR . '/blogs.dir' ) ) . '<br>';
	}

	echo '<i>WordPress</i>: ' . iv_format_size( $wp_space );
}

function iv_foldersize( $path ) {
	$total_size = 0;
	$files      = scandir( $path );
	$clean_path = rtrim( $path, '/' ) . '/';

	foreach( $files as $t ) {
		if ( '.' != $t && '..' != $t ) {
			$current_file = $clean_path . $t;

			if ( is_dir( $current_file ) ) {
				$size = iv_foldersize( $current_file );
				$total_size += $size;
			} else {
				$size = filesize( $current_file );
				$total_size += $size;
			}
		}
	}

	return $total_size;
}

function iv_format_size($size) {
	$units = explode( ' ', 'B KB MB GB TB PB' );

	$mod = 1024;

	for ( $i = 0; $size > $mod; $i++ )
		$size /= $mod;

	$end_index = strpos( $size, "." ) + 3;

	return substr( $size, 0, $end_index ) . ' ' . $units[$i];
}