WooCommerce - Change Number of Related Products displayed on the Product page

gistfile1.php

<?php
// Add this to your theme's functions.php file

remove_action( 'woocommerce_after_single_product_summary', 'woocommerce_output_related_products', 20 );
function custom_output_related_products() {
  // Display 5 products in 5 columns
  woocommerce_related_products( 5, 5 );
}
add_action( 'woocommerce_after_single_product_summary', 'custom_output_related_products', 20 );