From http://www.wpsite.net/limit-excerpt-length-words-wordpress/

wp_string_limit_words

/* ********************
* Limit post excerpts. Within theme files used as
* print string_limit_words(get_the_excerpt(), 20);
******************************************************************** */
function string_limit_words($string, $word_limit) { $words = explode(' ', $string, ($word_limit + 1)); if(count($words) > $word_limit) array_pop($words); return implode(' ', $words); }