Conditioning WP post per page

I have this code which works okay for what I wanted but I will probably need to put a condition if there's only 2 posts then wrap it in a <div class="large-6"> then if there's 3 posts then wrap it in large-4.

Just a little confused how to add a condition statement.

<?php

$loop = new WP_Query( array( 'post_type' => 'portfolio', 'posts_per_page' => '3', 'offset' => '1' ) );

?>

<?php while ( $loop->have_posts() ) : $loop->the_post(); ?>

<div class="large-4 columns">

<h5><?php the_title(); ?></h5>

<?php edit_post_link(); // Always handy to have Edit Post Links available ?>

<?php if ( has_post_thumbnail()) : // Check if thumbnail exists ?>

<?php echo get_the_post_thumbnail(); ?>

<?php endif; ?>

</div>

<?php endwhile; ?>