Script for estimate the space required by index before creation

Following script helps to get the required space for index creation before actual creating it.

SET SERVEROUTPUT ON
DECLARE
v_used_bytes NUMBER(10);
v_Allocated_Bytes NUMBER(10);
BEGIN
DBMS_SPACE.CREATE_INDEX_COST
( 'create index HR.EMP_INDEX_EMPNO on HR.EMPLOYEES(EMPNO)',
v_used_Bytes,
v_Allocated_Bytes
); 
DBMS_OUTPUT.PUT_LINE('Used Bytes MB: ' || round(v_used_Bytes/1024/1024));
DBMS_OUTPUT.PUT_LINE('Allocated Bytes MB: ' || round(v_Allocated_Bytes/1024/1024));
END;
/