What Does the (10) in MySQL INT(10) Really Mean? Understanding Display Width and ZEROFILL

1. Meaning

In MySQL, the number in parentheses after INT (e.g., INT(10)) specifies the display width, which only affects how values are padded with leading zeros when the ZEROFILL attribute is used. The storage size of INT is always 4 bytes (32 bits) regardless of the display width.

Storage space: INT always occupies 4 bytes.

Range: Signed INT: -2147483648 to 2147483647; INT UNSIGNED: 0 to 4294967295. Display width does not change this range.

2. Using ZEROFILL

When ZEROFILL is added to an INT column, MySQL pads the value with leading zeros to match the specified display width.

CREATE TABLE users (
  id INT(10) ZEROFILL,
  name VARCHAR(50)
);
INSERT INTO users (id, name) VALUES (123, 'Alice');
SELECT * FROM users;

The query returns the id as 0000000123, achieving a 10‑digit width.

3. Changes in MySQL 8.0.17 and later

Starting with MySQL 8.0.17, the display width for integer types is deprecated and ignored unless used with ZEROFILL. It is recommended to define INT without a width unless compatibility requires it.

Impact: INT(10) is ignored unless ZEROFILL is present.

Recommendation: Use plain INT.

Examples without ZEROFILL show that the width does not affect output, while with ZEROFILL the values are padded to the defined width.

4. Summary

The number in INT(10) is a display width used only with ZEROFILL to add leading zeros.

It does not affect storage size or numeric range.

From MySQL 8.0.17 onward, display width is deprecated; avoid relying on it unless necessary.