SELECT CONCAT(table_schema, '.', table_name),
CONCAT(ROUND(table_rows / 1000000, 2), 'M') rows,
CONCAT(ROUND(data_length / ( 1024 * 1024 * 1024 ), 2), 'G') DATA,
CONCAT(ROUND(index_length / ( 1024 * 1024 * 1024 ), 2), 'G') idx,
CONCAT(ROUND(( data_length + index_length ) / ( 1024 * 1024 * 1024 ), 2), 'G') total_size,
ROUND(index_length / data_length, 2) idxfrac
FROM information_schema.TABLES
ORDER BY data_length + index_length DESC
LIMIT 10;
+-------------------------------------+--------+--------+--------+------------+---------+
| concat(table_schema,'.',table_name) | rows | data | idx | total_size | idxfrac |
+-------------------------------------+--------+--------+--------+------------+---------+
| art87.link_out87 | 37.25M | 14.83G | 14.17G | 29.00G | 0.96 |
| art87.article87 | 12.67M | 15.83G | 4.79G | 20.62G | 0.30 |
| art116.article116 | 10.49M | 12.52G | 3.65G | 16.18G | 0.29 |
| art84.article84 | 10.10M | 10.11G | 3.59G | 13.70G | 0.35 |
| art104.link_out104 | 23.66M | 6.63G | 6.55G | 13.18G | 0.99 |
| art118.article118 | 7.06M | 10.49G | 2.68G | 13.17G | 0.26 |
| art106.article106 | 9.86M | 10.19G | 2.76G | 12.95G | 0.27 |
| art85.article85 | 6.20M | 9.82G | 2.51G | 12.33G | 0.26 |
| art91.article91 | 8.66M | 9.17G | 2.66G | 11.83G | 0.29 |
| art94.article94 | 5.21M | 10.10G | 1.69G | 11.79G | 0.17 |
+-------------------------------------+--------+--------+--------+------------+---------+
10 rows in set (2 min 29.19 sec)
http://www.mysqlperformanceblog.com/2008/02/04/finding-out-largest-tables-on-mysql-server/