SQL SERVER - How to measure size of DB or table

Use this stored procedure:

use framework;
exec sp_spaceused;

Output:

database_name                         database_size      unallocated space
------------------------------------- ------------------ ------------------
framework                             7.50 MB            0.94 MB

reserved           data               index_size         unused
------------------ ------------------ ------------------ ------------------
5184 KB            2816 KB            1808 KB            560 KB

For question to concrete table add its name as parameter:

use framework;
exec sp_spaceused 'users';

Output:

name   rows        reserved           data               index_size         unused
------ ----------- ------------------ ------------------ ------------------ ------
users  40          16 KB              8 KB               8 KB               0 KB