Calculate Database/Table size in MySQL

MySQL is an open-source relational database management system (RDBMS) available under the terms of the GNU General Public License, as well as under a variety of proprietary agreements.

Thanks to some few functions, it's possible to retrieve important information about database size and/or table size for a MySQL instance.

Size for all databases

SELECT table_schema "Database Name", SUM(data_length+index_length)/1024/1024
"Database Size (MB)" FROM information_schema.TABLES GROUP BY table_schema;
+---------------------+--------------------+
| Database Name | Database Size (MB) |
+---------------------+--------------------+
| db_1 | 113.51562500 |
| db_2 | 172.59375000 |
| db_3 | 48.70312500 |
| db_4 | 1830.53125000 |
| db_5 | 432.89062500 |
| information_schema | 0.07812500 |
| mysql | 1.03164101 |
| performance_schema | 0.00000000 |
+---------------------+--------------------+
8 rows in set (0.41 sec)

Size of tables for a specific database

SELECT table_name "Table Name", table_rows "Rows Count", round(((data_length + index_length)/1024/1024),2) "Table Size (MB)" FROM information_schema.TABLES WHERE table_schema = "db_4";
+-------------------------------+------------+-----------------+
| Table Name | Rows Count | Table Size (MB) |
+-------------------------------+------------+-----------------+
| table_1 | 245 | 0.05 |
| table_2 | 1 | 0.03 |
| table_3 | 537 | 0.11 |
| table_4 | 1 | 0.05 |
| table_5 | 57 | 0.05 |
| table_6 | 0 | 0.05 |
| table_7 | 2 | 0.05 |
| table_8 | 584 | 0.13 |
| table_9 | 48 | 0.03 |
| table_10 | 12972 | 2.16 |
| table_11 | 584 | 0.11 |
[ ... ]
| table_50 | 0 | 0.05 |
| table_51 | 119864 | 16.03 |
| table_52 | 146688 | 9.55 |
| table_53 | 48 | 0.05 |
| table_54 | 852591 | 208.30 |
| table_55 | 138786 | 66.64 |
| table_56 | 47 | 0.08 |
| table_57 | 169 | 0.09 |
| table_58 | 0 | 0.03 |
+-------------------------------+------------+-----------------+
58 rows in set (0.00 sec)
For a complete documentation, please refer to the official documentation on their website https://www.mysql.com