How to increase number of grids over front page

Can anybody explain how can I increase grids shown in my front page from 10 to 12. My website link : http://surfthelist.com/.
Code at index.php :

<?php
		        $count = 1;
		    ?>
			<?php if (have_posts()) : while ( have_posts() ) : the_post() ?>

		    	<?php include('includes/loop.php'); ?>

		        <?php if ( $count%3 == 0 ) { ?>

		            <div class="clear"></div>

		        <?php }; $count++; ?>

			<?php endwhile; ?>