I got an email from my hosting provider that I was exceeding my wordpress database space of 1000MB, which I thought was very strange. Had 2 dabases in which I each imported content of about 50MB (gzip format). I could not find the actual database size so I did some digging around and found the SQL code below which does the trick:

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 ;

The result for my database is 595MB, so it seems actually right that with two databases (copy datatabase) I’m exceeding 1000Mb.

There also is an option to enable Statistics on the database but this can slowdown you server / database and cause a lot fo traffic between webserver and MySQL server. This option can be found in phpMyAdin -> databases -> enable statistics gecheckbox.

UPDATE:

There seems to be a ‘easier’ way to show the WordPress database size. In the tabel overview scroll all the way down. At the bottom the total size is shown,  duh 🙂