In Wordpress, default Height / Width for image uploaded (from admin) in single page is 400x300 px ! If u want more: Open file /wp-includes/post-template.php find function: prepend_attachment($content) and modify this: get_the_attachment_link(false, true, array(400, 300)); with this: get_the_attachment_link(false, true, array(600, 400)); DONE. For now all image will have default ...