Calculate Export dump size

The following query calculates how much table data each schema takes on your database

SELECT owner, ROUND(SUM(size_mb)) MBytes FROM 
(
SELECT owner, segment_name, segment_type, partition_name, ROUND(bytes/(1024*1024),2) SIZE_MB, tablespace_name 
FROM DBA_SEGMENTS 
WHERE SEGMENT_TYPE IN ('TABLE', 'TABLE PARTITION', 'TABLE SUBPARTITION') 
--AND TABLESPACE_NAME LIKE 'COSTE%' 
--AND SEGMENT_NAME LIKE 'OE_ORDER_LINES_ALL%' 
--AND partition_name LIKE 'USAGE_FCT_NEW%'
--AND OWNER = 'TARGET_DW' 
--AND ROUND(bytes/(1024*1024),2) > 1000)
) 
GROUP BY owner 
ORDER BY MBytes DESC;