float and real (Transact-SQL)

Approximate-number data types for use with floating point numeric data. Floating point data is approximate; therefore, not all values in the data type range can be represented exactly.

The SQL-92 synonym for real is float(24).

Data type Range Storage


- 1.79E+308 to -2.23E-308, 0 and 2.23E-308 to 1.79E+308

Depends on the value of n


- 3.40E + 38 to -1.18E - 38, 0 and 1.18E - 38 to 3.40E + 38

4 Bytes

Topic link icon Transact-SQL Syntax Conventions

float [ ( n ) ]

Where n is the number of bits that are used to store the mantissa of the float number in scientific notation and, therefore, dictates the precision and storage size. If n is specified, it must be a value between 1 and 53. The default value of n is 53.

n value Precision Storage size


7 digits

4 bytes


15 digits

8 bytes

SQL Server 2005 treats n as one of two possible values. If 1<=n<=24, n is treated as 24. If 25<=n<=53, n is treated as 53.

The SQL Server float[(n)] data type complies with the SQL-92 standard for all values of n from 1 through 53. The synonym for double precision is float(53).