How to get the total database size in MySQL using a query

Getting the total database size in MySQL is not hard. It basically requires a simple if-statement.

NB.: this article might work on other platforms as well, but I didn't personally test those. If you do, please let me know!

Run the following SELECT statement on your database. Make sure to add the name of your database at the end:

SELECT
    size_mb
FROM (
    SELECT
        table_schema as name,
        ROUND(SUM(data_length + index_length) / 1024 / 1024, 1) as size_mb
    FROM
        information_schema.tables
    GROUP BY
        table_schema) alias_one
WHERE
    name = 'your_database_name'

And the result:

The query will get the total size of the database in MB. If you want the size in GB, you should add another divide by 100 like the below query. For more precise numbers, update the second parameter of the ROUND function to the number of decimals you want (e.g. 2 decimals for a precision like 4.71GB:

SELECT
    size_gb
FROM (
    SELECT
        table_schema as name,
        ROUND(SUM(data_length + index_length) / 1024 / 1024 / 1000, 2) as size_gb
    FROM
        information_schema.tables
    GROUP BY
        table_schema) alias_one
WHERE
    name = 'your_database_name'

Getting the size of all databases in the current MySQL instance

You can get even get a list of all the database sizes for the current MySQL instance. You can do so by removing the outer SELECT with the WHERE and only keep the inner SELECT statement:

SELECT
    table_schema AS name,
    ROUND(SUM(data_length + index_length) / 1024 / 1024 / 1000, 2) AS size_gb
FROM
    information_schema.tables
GROUP BY
    table_schema