Using T-SQL to ascertain the sizes of all the databases in an instance is really easy. The T-SQL below will show the sizes all of the databases at once in MB. This includes the sizes data and the log files combined for all databases.

SELECT DB_NAME(database_id) AS DatabaseName,
sum((size*8)/1024) as SizeOfDatabase
FROM sys.master_files
group by database_id

If you want to see all the database log file sizes

SELECT DB_NAME (mf . database_id) AS DatabaseName , sum ((size * 8)/ 1024 ) as SizeOfDatabase
FROM sys .master_files as mf
WHERE mf. type = 1 -- 1 refers to log
group by mf.database_id

If you want to see all the database data file sizes

SELECT DB_NAME (mf. database_id) AS DatabaseName, sum((size *8)/ 1024) as SizeOfDatabase
FROM sys .master_files as mf
WHERE DB_NAME (mf. database_id) in ( select d. name from sys.databases as d )
and mf. [type] <> 1 -- NOT 1 refers to log, anything not 1 is not a log
group by mf.database_id

Easy!