SQL Script to display sizes of all MS SQL databases in both MB and GB.

 SELECT d.NAME

    ,ROUND(SUM(CAST(mf.size AS bigint)) * 8 / 1024, 0) Size_MBs

    ,(SUM(CAST(mf.size AS bigint)) * 8 / 1024) / 1024 AS Size_GBs

FROM sys.master_files mf

INNER JOIN sys.databases d ON d.database_id = mf.database_id

WHERE d.database_id > 4 -- Skip system databases

GROUP BY d.NAME

ORDER BY d.NAME