WordPress: ACF: get uploaded file size
<?php
$attachment_id = get_field('dl-fb2');
$url = wp_get_attachment_url( $attachment_id );
$title = get_the_title( $attachment_id );
$myfile = filesize( get_attached_file( $attachment_id ) );
$bytes = size_format($myfile, 2);
if(get_field('dl-fb2')) { ?>
<tr>
<td><a href="<?php echo $url; ?>" title="<?php echo $title; ?>">Скачать в формате fb2</a></td>
<td>Размер файла: <?php echo $bytes; ?></td>
</tr>
<?php } ?>