Character data entered using extended site-defined client character sets should be stored in columns defined as Unicode. The UNICODE server character set requires two bytes of storage per character so that a CHAR(5) CHARACTER SET UNICODE field occupies 10 bytes of storage.
Given the 64000 byte limit on column size, a column cannot exceed 32000 characters. Furthermore, the combination of character data and other data types cannot exceed the 64000 byte limit on row size.