SIZE OF THE DATABASE FILES

SELECT name AS [File Name] , file_id, physical_name AS [Physical Name],
size/128 AS [Total Size in MB],
size/128.0 - CAST(FILEPROPERTY(name, 'SpaceUsed') AS int)/128.0
AS [Available Space In MB]
FROM sys.database_files;

OUTPUT
File Name file_id Physical Name Total Size in MB Available Space In MB
-------------------------------------------------------------------------------------------------------------------------------- ----------- ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- ---------------- ---------------------------------------
master 1 D:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\DATA\master.mdf 80 71.625000
mastlog 2 D:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\DATA\mastlog.ldf 1 0.640625

(2 row(s) affected)