Modify length of word in the_excerpt function wordpress

Default length of words in the_excerpt function wordpress is 55 words . How to modify it ? when you think it is too long or you want more words to display it ?

– Adding this function in wp-includes/formatting.php

function string_limit_words($string, $word_limit)
$words = explode(‘ ‘, $string, ($word_limit + 1));
if(count($words) > $word_limit)
return implode(‘ ‘, $words);

– add this line in templates page that you want to display the_excerpt

<?php $excerpt = get_the_excerpt(); echo string_limit_words($excerpt, n); ?>

n : number of word that you want to display .