Instead of the CHAR data type, you can use VARCHAR for variable-length character data, NCHAR for international Unicode data or NVARCHAR for variable-length Unicode.

While it probably doesn't matter for this column, do note that SQL Server has an nvarchar type that supports unicode. char and varchar store content in the local collation and thus are limited.

There's also the point that the storage engine may very well just allocate 8 characters no matter what even if a varchar is requested. 8 (or 16, for nchar) extra bytes in a row really isn't all ...