CHAR_LENGTH

Return the number of characters in a string. (The LENGTH function also returns the number of characters.)

CHAR_LENGTH | CHARACTER_LENGTH (string)

For example:

premdb=# SELECT LENGTH(nickname), CHAR_LENGTH(nickname) FROM team WHERE city='London';
 length | char_length 
--------+-------------
      7 |           7
      7 |           7
     10 |          10
      6 |           6
      9 |           9
      5 |           5
      5 |           5
      7 |           7
      4 |           4
(9 rows)

premdb=# SELECT MAX(CHARACTER_LENGTH(name)) FROM team;
 max 
-----
  23
(1 row)