# float and real (Transact-SQL)

**APPLIES TO:** SQL Server Azure SQL Database Azure Synapse Analytics (SQL DW) Parallel Data Warehouse

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 ISO synonym for **real** is **float(24)**.

Transact-SQL Syntax Conventions

## Syntax

**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 |
---|---|---|

1-24 |
7 digits | 4 bytes |

25-53 |
15 digits | 8 bytes |

Note

SQL Server 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 ISO standard for all values of *n* from **1** through **53**. The synonym for **double precision** is **float(53)**.

## Remarks

Data type | Range | Storage |
---|---|---|

float |
- 1.79E+308 to -2.23E-308, 0 and 2.23E-308 to 1.79E+308 | Depends on the value of n |

real |
- 3.40E + 38 to -1.18E - 38, 0 and 1.18E - 38 to 3.40E + 38 | 4 Bytes |

## Converting float and real data

Values of **float** are truncated when they are converted to any integer type.

When you want to convert from **float** or **real** to character data, using the STR string function is usually more useful than CAST( ). This is because STR enables more control over formatting. For more information, see STR (Transact-SQL) and Functions (Transact-SQL).

Prior to SQL Server 2016 (13.x), conversion of **float** values to **decimal** or **numeric** is restricted to values of precision 17 digits only. Any **float** value less than 5E-18 (when set using either the scientific notation of 5E-18 or the decimal notation of 0.0000000000000000050000000000000005) rounds down to 0. This is no longer a restriction as of SQL Server 2016 (13.x).

## See also

ALTER TABLE (Transact-SQL)

CAST and CONVERT (Transact-SQL)

CREATE TABLE (Transact-SQL)

Data Type Conversion (Database Engine)

Data Types (Transact-SQL)

DECLARE @local_variable (Transact-SQL)

SET @local_variable (Transact-SQL)