get_dirsize example

/** * Filters the amount of storage space used by the current site, in megabytes. * * @since 3.5.0 * * @param int|false $space_used The amount of used space, in megabytes. Default false. */
    $space_used = apply_filters( 'pre_get_space_used', false );

    if ( false === $space_used ) {
        $upload_dir = wp_upload_dir();
        $space_used = get_dirsize( $upload_dir['basedir'] ) / MB_IN_BYTES;
    }

    return $space_used;
}

/** * Returns the upload quota for the current blog. * * @since MU (3.0.0) * * @return int Quota in megabytes. */