---
title: "LOG10 (Transact-SQL)"
description: "LOG10 (Transact-SQL)"
author: markingmyname
ms.author: maghan
ms.date: "03/06/2017"
ms.prod: sql
ms.technology: t-sql
ms.topic: reference
f1_keywords:
  - "LOG10"
  - "LOG10_TSQL"
helpviewer_keywords:
  - "float expressions"
  - "LOG10 function"
  - "base-10 logarithms"
  - "logarithm of expression"
dev_langs:
  - "TSQL"
monikerRange: ">= aps-pdw-2016 || = azuresqldb-current || = azure-sqldw-latest || >= sql-server-2016 || >= sql-server-linux-2017 || = azuresqldb-mi-current"
---
# LOG10 (Transact-SQL)
[!INCLUDE [sql-asdb-asdbmi-asa-pdw](../../includes/applies-to-version/sql-asdb-asdbmi-asa-pdw.md)]

  Returns the base-10 logarithm of the specified **float** expression.  
  
 ![Topic link icon](../../database-engine/configure-windows/media/topic-link.gif "Topic link icon") [Transact-SQL Syntax Conventions](../../t-sql/language-elements/transact-sql-syntax-conventions-transact-sql.md)  
  
## Syntax  
  
```syntaxsql  
LOG10 ( float_expression )  
```  
  
[!INCLUDE[sql-server-tsql-previous-offline-documentation](../../includes/sql-server-tsql-previous-offline-documentation.md)]

## Arguments
 *float_expression*  
 Is an [expression](../../t-sql/language-elements/expressions-transact-sql.md) of type **float** or of a type that can be implicitly converted to **float**.  
  
## Return Types  
 **float**  
  
## Remarks  
 The LOG10 and POWER functions are inversely related to one another. For example, 10 ^ LOG10(*n*) = *n*.  
  
## Examples  
  
### A. Calculating the base 10 logarithm for a variable.  
 The following example calculates the `LOG10` of the specified variable.  
  
```sql  
DECLARE @var FLOAT;  
SET @var = 145.175643;  
SELECT 'The LOG10 of the variable is: ' + CONVERT(VARCHAR,LOG10(@var));  
GO  
```  
  
 [!INCLUDE[ssResult](../../includes/ssresult-md.md)]  
  
```  
The LOG10 of the variable is: 2.16189      
  
(1 row(s) affected)  
```  
  
### B. Calculating the result of raising a base-10 logarithm to a specified power.  
 The following example returns the result of raising a base-10 logarithm to a specified power.  
  
```sql  
SELECT POWER (10, LOG10(5));   
```  
  
 [!INCLUDE[ssResult](../../includes/ssresult-md.md)]  
  
```  
-----------  
5  
  
(1 row(s) affected)  
```  
  
## Examples: [!INCLUDE[ssSDWfull](../../includes/sssdwfull-md.md)] and [!INCLUDE[ssPDW](../../includes/sspdw-md.md)]  
  
### C: Calculating the base 10 logarithm for a value.  
 The following example calculates the `LOG10` of the specified value.  
  
```sql  
SELECT LOG10(145.175642);  
```  
  
 [!INCLUDE[ssResult](../../includes/ssresult-md.md)]  
  
 ```
-------------------  
2.16
```  
  
## See Also  
 [Mathematical Functions (Transact-SQL)](../../t-sql/functions/mathematical-functions-transact-sql.md)   
 [POWER (Transact-SQL)](../../t-sql/functions/power-transact-sql.md)   
 [LOG (Transact-SQL)](../../t-sql/functions/log-transact-sql.md)