int, bigint, smallint, and tinyint
Exact number data types that use integer data.
bigint
Integer (whole number) data from -2^63 (-9223372036854775808) through 2^63-1 (9223372036854775807). Storage size is 8 bytes.
int
Integer (whole number) data from -2^31 (-2,147,483,648) through 2^31 - 1 (2,147,483,647). Storage size is 4 bytes. The SQL-92 synonym for int is integer.
smallint
Integer data from -2^15 (-32,768) through 2^15 - 1 (32,767). Storage size is 2 bytes.
tinyint
Integer data from 0 through 255. Storage size is 1 byte.
Remarks
The bigint data type is supported where integer values are supported. However, bigint is intended for special cases where the integer values may exceed the range supported by the int data type. The int data type remains the primary integer data type in SQL Server.
bigint fits between smallmoney and int in the data type precedence chart.
Functions will return bigint only if the parameter expression is a bigint data type. SQL Server will not automatically promote other integer data types (tinyint, smallint, and int) to bigint.