The WordPress UI is designed for ease of use but occasionally modifications can help users when managing the site. One such modification is to increase the default height of the Excerpt field on the Post edit screen. This is helpful if all your Posts or Custom Post Types have longer than normal excerpts.

To increase the height just add the following code to your themes functions.php file. To customize, just modify to your desired pixel height.

/* ----------------------------------------------------------
  Increase default excerpt box height on back end
---------------------------------------------------------- */

add_action('admin_head', 'excerpt_textarea_height');
function excerpt_textarea_height() {
	echo'
	<style type="text/css">
		#excerpt{ height:150px; }
	</style>
	';
}