How to Change the Length of Excerpts in WordPress

Simple little function here for the next time you need to control how many characters the_excerpt tag shows.

function custom_excerpt_length( $length ) {
    return 20;
}
add_filter( 'excerpt_length', 'custom_excerpt_length', 999 );

Just add the code above into the functions.php file. You can read more about this on the Codex.