function excerpt($limit) {
      $excerpt = explode(' ', get_the_excerpt(), $limit);
      if (count($excerpt)>=$limit) {
        array_pop($excerpt);
        $excerpt = implode(" ",$excerpt).'...';
      } else {
        $excerpt = implode(" ",$excerpt);
      } 
      $excerpt = preg_replace('`\[[^\]]*\]`','',$excerpt);
      return $excerpt;
    }

    function content($limit) {
      $content = explode(' ', get_the_content(), $limit);
      if (count($content)>=$limit) {
        array_pop($content);
        $content = implode(" ",$content).'...';
      } else {
        $content = implode(" ",$content);
      } 
      $content = preg_replace('/\[.+\]/','', $content);
      $content = apply_filters('the_content', $content); 
      $content = str_replace(']]>', ']]>', $content);
      return $content;
    }

http://stackoverflow.com/questions/4082662/multiple-excerpt-lengths-in-wordpress

then in your template code you just use..

echo excerpt(25);

Multiple excerpt lengths in wordpress

wordpress

PHP