SELECT
DB_NAME(database_id) AS 'Database Name',
REPLACE(CONVERT(VARCHAR, CAST(SUM(size) * 8.0 / 1024 AS DECIMAL(10,2)), 111), '.', ',') AS 'Size_MB',
REPLACE(CONVERT(VARCHAR, CAST(SUM(size) * 8.0 / 1048576 AS DECIMAL(10,2)), 111), '.', ',') AS 'Size_GB',
REPLACE(CONVERT(VARCHAR, CAST(SUM(size) * 8.0 / 1073741824 AS DECIMAL(10,2)), 111), '.', ',') AS 'Size_TB'
FROM sys.master_files
GROUP BY database_id
ORDER BY SUM(size) * 8.0 / 1024 DESC;