how much space does sql server take per row

1SELECT 
2    TableName = t.NAME,
3    SchemaName = s.Name,
4    [RowCount] = p.rows,
5    TotalSpaceMB = CONVERT(DECIMAL(18,2), SUM(a.total_pages) * 8 / 1024.0), 
6    UsedSpaceMB = CONVERT(DECIMAL(18,2), SUM(a.used_pages) * 8 / 1024.0),
7    UnusedSpaceMB = CONVERT(DECIMAL(18,2), (SUM(a.total_pages) - SUM(a.used_pages)) * 8 / 1024.0)
8FROM 
9    sys.tables t
10    INNER JOIN sys.indexes i ON t.OBJECT_ID = i.object_id
11    INNER JOIN sys.partitions p ON i.object_id = p.OBJECT_ID AND i.index_id = p.index_id
12    INNER JOIN sys.allocation_units a ON p.partition_id = a.container_id
13    LEFT OUTER JOIN sys.schemas s ON t.schema_id = s.schema_id
14WHERE 
15    t.NAME NOT LIKE 'dt%' 
16    AND t.is_ms_shipped = 0
17    AND i.OBJECT_ID > 255 
18GROUP BY 
19    t.Name, 
20    s.Name, 
21    p.Rows
22ORDER BY 
23    TotalSpaceMB DESC
24