Calculate the size of all tables in the database in megabytes

Sql_tbl-size

-- Calculate the size of all tables in the database in megabytes
SELECT 
    t.NAME AS TableName,
    p.rows AS RowCounts,
    SUM(a.total_pages) * 8 / 1024 AS TotalSpaceMB, 
    SUM(a.used_pages) * 8 / 1024 AS UsedSpaceMB, 
    (SUM(a.total_pages) - SUM(a.used_pages)) * 8 / 1024 AS UnusedSpaceMB
FROM 
    sys.tables t
INNER JOIN      
    sys.indexes i ON t.OBJECT_ID = i.object_id
INNER JOIN 
    sys.partitions p ON i.object_id = p.OBJECT_ID AND i.index_id = p.index_id
INNER JOIN 
    sys.allocation_units a ON p.partition_id = a.container_id
GROUP BY 
    t.NAME, p.rows
ORDER BY 
    TotalSpaceMB desc;