BIT_LENGTH()
BIT_LENGTH(string)This function returns the number of bits in a given string. The following example uses the default character set, where one character requires 8 bits:
SELECT BIT_LENGTH('a') AS 'One Character',
BIT_LENGTH('ab') AS 'Two Characters';
+---------------+----------------+
| One Character | Two Characters |
+---------------+----------------+
| 8 | 16 |
+---------------+----------------+