custom postthumbnail size in wordpress code example

Example 1: wordpress get post thumbnail

<?php 
/* RETURNS a full image resource as: <img class="data..." src="data...">
   ALL parameters are optional. Not needed if you are on WP LOOP
*/
echo get_the_post_thumbnail( $the_query->ID, array( 500, 400) ); 
/* USE get_the_post_thumbnail_url() to get only the image url */
?>

Example 2: adding custom featured image size in wordpress

the_post_thumbnail(); // Without parameter ->; Thumbnail
the_post_thumbnail( 'thumbnail' ); // Thumbnail (default 150px x 150px max)
the_post_thumbnail( 'medium' ); // Medium resolution (default 300px x 300px max)
the_post_thumbnail( 'medium_large' ); // Medium-large resolution (default 768px x no height limit max)
the_post_thumbnail( 'large' ); // Large resolution (default 1024px x 1024px max)
the_post_thumbnail( 'full' ); // Original image resolution (unmodified)
the_post_thumbnail( array( 100, 100 ) ); // Other resolutions (height, width)