How to see size of postgres tables

SELECT pg_tables.tablename, pg_tables.schemaname, pg_size_pretty(pg_relation_size((pg_tables.schemaname::text || '.'::text) || pg_tables.tablename::text)) AS pg_size_pretty FROM pg_tables ORDER BY pg_relation_size((pg_tables.schemaname::text || '.'::text) || pg_tables.tablename::text) DESC;