Do INT(4) and INT(11) Really Differ? MySQL INT Types Explained

Origin

When designing a MySQL database, developers often see integer columns defined as INT with a number in parentheses, such as INT(4) or INT(11), and wonder what the number actually controls.

Storage Comparison

Three tables— t_int_four, t_int_eleven, and t_int_default —were created, each containing a column of type INT(4), INT(11), and plain INT respectively. Inserting the maximum signed integer value 2147483647 succeeded in all three tables, showing that the parenthesized number does not limit the numeric range nor affect storage.

Attempting to store an 11‑digit number (e.g., 12345678901) in INT(11) also failed because the signed INT range remains limited to 10 digits; the display width does not extend the range.

Inspecting the .ibd files of the three tables revealed that each row occupies exactly 4 bytes, confirming that storage size is independent of the number in parentheses.

ZEROFILL

The ZEROFILL attribute converts an integer column to UNSIGNED and pads displayed values with leading zeros up to the specified width. A table t_int_zerofill with columns my_int_four, my_int_eleven, and my_int_default was created, each defined with ZEROFILL. Inserting the value 1 produced 0001, 00000000001, and 0000000001 respectively, matching the widths 4, 11, and the default unsigned width (10 digits). Inserting 1234 stopped padding for the INT(4) column because the number already reached the defined width, while the other columns continued to pad.

Mixed Example

A table t_int_complex_zerofill containing various numeric types (TINYINT, SMALLINT, MEDIUMINT, INT, BIGINT) demonstrated that adding ZEROFILL does not change the actual storage size of any type; it only affects the visual representation.

Summary

The number in INT(M) is a display width, not a storage or range constraint. Without ZEROFILL, INT(4) and INT(11) behave identically—both occupy 4 bytes and share the same signed range. Developers may still write INT(11) as a visual cue that the column can hold up to the 10‑digit maximum of a signed INT, or use INT(4) to remind themselves of the 4‑byte storage size when optimizing table schemas.

INT(11): serves as a warning that inserting numbers longer than the signed INT’s 10‑digit maximum (e.g., 12345678901) would be illegal.

INT(4): indicates the column’s 4‑byte storage size, helping designers estimate overall row size alongside other column types.