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MySQL Globalization  /  ...  /  The utf8mb3 Character Set (3-Byte UTF-8 Unicode Encoding)

1.9.2 The utf8mb3 Character Set (3-Byte UTF-8 Unicode Encoding)

The utf8mb3 character set has these characteristics:

  • Supports BMP characters only (no support for supplementary characters)

  • Requires a maximum of three bytes per multibyte character.

Applications that use UTF-8 data but require supplementary character support should use utf8mb4 rather than utf8mb3 (see Section 1.9.1, “The utf8mb4 Character Set (4-Byte UTF-8 Unicode Encoding)”).

Exactly the same set of characters is available in utf8mb3 and ucs2. That is, they have the same repertoire.


The recommended character set for MySQL is utf8mb4. All new applications should use utf8mb4.

The utf8mb3 character set is deprecated. utf8mb3 remains supported for the lifetimes of the MySQL 8.0.x and following LTS release series, as well as in MySQL 8.0.

Expect utf8mb3 to be removed in a future major release of MySQL.

Since changing character sets can be a complex and time-consuming task, you should begin to prepare for this change now by using utf8mb4 for new applications. For guidance in converting existing applications which use utfmb3, see Section 1.9.8, “Converting Between 3-Byte and 4-Byte Unicode Character Sets”.

utf8mb3 can be used in CHARACTER SET clauses, and utf8mb3_collation_substring in COLLATE clauses, where collation_substring is bin, czech_ci, danish_ci, esperanto_ci, estonian_ci, and so forth. For example:

SELECT * FROM t WHERE s1 COLLATE utf8mb3_general_ci = 'x';
DECLARE x VARCHAR(5) CHARACTER SET utf8mb3 COLLATE utf8mb3_danish_ci;
SELECT CAST('a' AS CHAR CHARACTER SET utf8mb4) COLLATE utf8mb4_czech_ci;

Prior to MySQL 8.0.29, instances of utf8mb3 in statements were converted to utf8. In MySQL 8.0.30 and later, the reverse is true, so that in statements such as SHOW CREATE TABLE or SELECT CHARACTER_SET_NAME FROM INFORMATION_SCHEMA.COLUMNS or SELECT COLLATION_NAME FROM INFORMATION_SCHEMA.COLUMNS, users see the character set or collation name prefixed with utf8mb3 or utf8mb3_.

utf8mb3 is also valid (but deprecated) in contexts other than CHARACTER SET clauses. For example:

mysqld --character-set-server=utf8mb3
SET NAMES 'utf8mb3'; /* and other SET statements that have similar effect */
SELECT _utf8mb3 'a';

For information about data type storage as it relates to multibyte character sets, see String Type Storage Requirements.