MySQL Field Length description

Storage required for column types
Tinyint 1 byte
Smallint 2 bytes
Mediumint 3 bytes
Int 4 bytes
Integer 4 bytes
Bigint 8 bytes
Float (x) 4 if x <= 24 or 8 If 25 <= x <= 53
Float 4 bytes
Double 8 bytes
Double Precision 8 bytes
Real 8 bytes
Decimal (M, d) M bytes (D + 2, if m <D)
Numeric (M, d) M bytes (D + 2, if m <D)

Date and Time Type
Storage required for column types
Date 3 bytes
Datetime 8 bytes
Timestamp 4 bytes
Time 3 bytes
Year 1 byte

String type
Storage required for column types
Char (m) M bytes, 1 <= m <= 255
Varchar (m) L + 1 byte, where l <= m and 1 <= m <= 255
Tinyblob, tinytext L + 1 byte, here l <2 ^ 8
Blob, text L + 2 bytes, here l <2 ^ 16
Mediumblob, mediumtext L + 3 bytes, here l <2 ^ 24
Longblob, longtext L + 4 bytes, here l <2 ^ 32
Enum ('value1 ', 'value2',...) 1 or 2 bytes, depending on the number of enumerated values (maximum 65535)
Set ('value1 ', 'value2',...) 1, 2, 3, 4, or 8 bytes, depending on the number of set members (up to 64 members)