How to find a length of LOB column?

Using dbms_lob.getlength(column name) one can find the length of the LOB (CLOB/BLOB/BFILE) data type.

Example:
SQL> SELECT dbms_lob.getlength(lob_column) FROM scott.lob_table;

DBMS_LOB.GETLENGTH(lob_column)
——————————–
358
153