Extension to @xav answer that handled table partitions to get size in MB and GB.
Tested on SQL Server 2008/2012 (Commented a line where is_memory_optimized = 1
)
SELECT
a2.name AS TableName,
a1.rows as [RowCount],
--(a1.reserved + ISNULL(a4.reserved,0)) * 8 AS ReservedSize_KB,
--a1.data * 8 AS DataSize_KB,
--(CASE WHEN (a1.used + ISNULL(a4.used,0)) > a1.data THEN (a1.used + ISNULL(a4.used,0)) - a1.data ELSE 0 END) * 8 AS IndexSize_KB,
--(CASE WHEN (a1.reserved + ISNULL(a4.reserved,0)) > a1.used THEN (a1.reserved + ISNULL(a4.reserved,0)) - a1.used ELSE 0 END) * 8 AS UnusedSize_KB,
CAST(ROUND(((a1.reserved + ISNULL(a4.reserved,0)) * 8) / 1024.00, 2) AS NUMERIC(36, 2)) AS ReservedSize_MB,
CAST(ROUND(a1.data * 8 / 1024.00, 2) AS NUMERIC(36, 2)) AS DataSize_MB,
CAST(ROUND((CASE WHEN (a1.used + ISNULL(a4.used,0)) > a1.data THEN (a1.used + ISNULL(a4.used,0)) - a1.data ELSE 0 END) * 8 / 1024.00, 2) AS NUMERIC(36, 2)) AS IndexSize_MB,
CAST(ROUND((CASE WHEN (a1.reserved + ISNULL(a4.reserved,0)) > a1.used THEN (a1.reserved + ISNULL(a4.reserved,0)) - a1.used ELSE 0 END) * 8 / 1024.00, 2) AS NUMERIC(36, 2)) AS UnusedSize_MB,
--'| |' Separator_MB_GB,
CAST(ROUND(((a1.reserved + ISNULL(a4.reserved,0)) * 8) / 1024.00 / 1024.00, 2) AS NUMERIC(36, 2)) AS ReservedSize_GB,
CAST(ROUND(a1.data * 8 / 1024.00 / 1024.00, 2) AS NUMERIC(36, 2)) AS DataSize_GB,
CAST(ROUND((CASE WHEN (a1.used + ISNULL(a4.used,0)) > a1.data THEN (a1.used + ISNULL(a4.used,0)) - a1.data ELSE 0 END) * 8 / 1024.00 / 1024.00, 2) AS NUMERIC(36, 2)) AS IndexSize_GB,
CAST(ROUND((CASE WHEN (a1.reserved + ISNULL(a4.reserved,0)) > a1.used THEN (a1.reserved + ISNULL(a4.reserved,0)) - a1.used ELSE 0 END) * 8 / 1024.00 / 1024.00, 2) AS NUMERIC(36, 2)) AS UnusedSize_GB
FROM
(SELECT
ps.object_id,
SUM (CASE WHEN (ps.index_id < 2) THEN row_count ELSE 0 END) AS [rows],
SUM (ps.reserved_page_count) AS reserved,
SUM (CASE
WHEN (ps.index_id < 2) THEN (ps.in_row_data_page_count + ps.lob_used_page_count + ps.row_overflow_used_page_count)
ELSE (ps.lob_used_page_count + ps.row_overflow_used_page_count)
END
) AS data,
SUM (ps.used_page_count) AS used
FROM sys.dm_db_partition_stats ps
--===Remove the following comment for SQL Server 2014+
--WHERE ps.object_id NOT IN (SELECT object_id FROM sys.tables WHERE is_memory_optimized = 1)
GROUP BY ps.object_id) AS a1
LEFT OUTER JOIN
(SELECT
it.parent_id,
SUM(ps.reserved_page_count) AS reserved,
SUM(ps.used_page_count) AS used
FROM sys.dm_db_partition_stats ps
INNER JOIN sys.internal_tables it ON (it.object_id = ps.object_id)
WHERE it.internal_type IN (202,204)
GROUP BY it.parent_id) AS a4 ON (a4.parent_id = a1.object_id)
INNER JOIN sys.all_objects a2 ON ( a1.object_id = a2.object_id )
INNER JOIN sys.schemas a3 ON (a2.schema_id = a3.schema_id)
WHERE a2.type <> N'S' and a2.type <> N'IT'
--AND a2.name = 'MyTable' --Filter for specific table
--ORDER BY a3.name, a2.name
ORDER BY ReservedSize_MB DESC