How Many Characters Can MySQL 5.7 VARCHAR Store? Limits by Charset Explained

Background

MySQL stores VARCHAR values with a 1‑ or 2‑byte length prefix, and the total row size cannot exceed 65,535 bytes. The actual number of characters that fit depends on the character set’s maximum bytes per character and on row‑format overhead such as the NULL‑flag byte.

latin1 Character Set

Attempting to create a table with varchar(65535) under latin1 fails with the error “Row size too large…”. Reducing the column length to 65,532 succeeds, confirming that the 2‑byte length prefix consumes 2 bytes, leaving a practical limit of 65533 characters.

create table tinywan(name varchar(65535)) charset=latin1;

Result:

Row size too large

create table tinywan(name varchar(65532)) charset=latin1;

Result:

Query OK

utf8mb4 Character Set

With the default database charset set to utf8mb4, the maximum row size remains 65,535 bytes, but each character can occupy up to 4 bytes. Therefore the theoretical maximum column length is floor(65535/4) = 16383. However, when the column is defined as a primary key, InnoDB’s index‑key limit of 3072 bytes applies.

create table tinywan3(name varchar(16383) primary key);

Result: Specified key was too long; max key length is 3072 bytes Since the index key length is measured in bytes, the maximum safe primary‑key length for utf8mb4 is 3072 / 4 = 768 characters.

create table tinywan3(name varchar(768) primary key) charset=utf8mb4;

Result:

Query OK

utf8 Character Set

For utf8, each character can use up to 3 bytes. The primary‑key limit becomes 3072 / 3 ≈ 1024 characters, while a non‑indexed VARCHAR can theoretically store up to floor(65535/3) = 21845 characters. Because of the 2‑byte length prefix, the actual maximum without an index is 21844 characters.

create table tinywan32(name varchar(21844) not null) charset=utf8;

Result:

Query OK

Conclusions

In latin1, a VARCHAR column can store up to 65533 characters.

In utf8, a non‑indexed VARCHAR can store up to 21844 characters; as a primary key the safe limit is 1024 characters.

In utf8mb4, a non‑indexed VARCHAR can store up to 16383 characters; as a primary key the safe limit is 768 characters.