Because I don’t like searching for the same information twice, this is a short memo on how to find out the size of any given database in phpMyAdmin.
Just call following in the SQL query

SELECT table_schema "Data Base Name",
sum( data_length + index_length ) / 1024 / 1024 "Data Base Size in MB"
FROM information_schema.TABLES GROUP BY table_schema ;

Source: uponmyshoulder.com