The following SQL command lists each database on a given server shows its data file size.

with fs
as
 (
  select database_id, type, size * 8.0 / 1024 size
  from sys.master_files
 )
select 
 name,
 (select sum(size) from fs where type = 0 and fs.database_id = db.database_id) DataFileSizeMB,
 (select sum(size) from fs where type = 1 and fs.database_id = db.database_id) LogFileSizeMB
from sys.databases db