For SQL, the bytes required for CHAR or VARCHAR fields depends on whether the code page is single-byte, double-byte, or triple-byte. For example, a CHAR(4) field requires a maximum of 4 bytes if the code page is single byte, a maximum of 8 bytes if the code page is double-byte, and a maximum of 12 bytes if the code page is triple-byte.
Note: If you define a field as CHAR(10000) and the code page is UTF-8, which is a triple byte, the field requires a maximum of 30,000 bytes of storage.