add_action( 'woocommerce_before_shop_loop_item_title', 'bbloomer_show_sale_percentage_loop', 25 );

  


function bbloomer_show_sale_percentage_loop() {


   global $product;


   if ( ! $product->is_on_sale() ) return;


   if ( $product->is_type( 'simple' ) ) {


      $max_percentage = ( ( $product->get_regular_price() - $product->get_sale_price() ) / $product->get_regular_price() ) * 100;


   } elseif ( $product->is_type( 'variable' ) ) {


      $max_percentage = 0;


      foreach ( $product->get_children() as $child_id ) {


         $variation = wc_get_product( $child_id );


         $price = $variation->get_regular_price();


         $sale = $variation->get_sale_price();


         if ( $price != 0 && ! empty( $sale ) ) $percentage = ( $price - $sale ) / $price * 100;


         if ( $percentage > $max_percentage ) {


            $max_percentage = $percentage;


         }


      }


   }


   if ( $max_percentage > 0 ) echo "<div class='sale-perc'>-" . round($max_percentage) . "%</div>";


}