Easily Change the Length of the Default WordPress Excerpt

The default WordPress excerpt is 55 words long. By adding this quick bit to your functions.php file you can change the length to better suite you theme:

{code type=php}
function new_excerpt_length($length) {
return 42;
}
add_filter(‘excerpt_length’, ‘new_excerpt_length’);
{/code}

Source: WordPress Codex