> For the complete documentation index, see [llms.txt](https://docs.fabricplan.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.fabricplan.com/documentation/plan/planning-sheets/formula-syntax/math-functions/log.md).

# LOG

The *LOG* function returns the logarithm of a number using a specified base. It calculates the exponent to which the base must be raised to produce the given number. This function is commonly used in mathematical, financial, and scientific calculations involving exponential relationships or scale transformations.

#### Syntax

```javascript
LOG(value, base)
```

#### Arguments

* `value`: The positive real number for which to calculate the logarithm.
* `base`: The base of the logarithm.

#### Return value

Returns the logarithm of the specified value for the given base.

#### Example

```javascript
LOG(Sales, 10)
```

In this example, the LOG function is used to create the *Log\_Sales* measure, which returns the logarithm of the values in the *Sales* measure using base 10.

<figure><img src="/files/R3oMS4iz9CHWZm10P2EO" alt=""><figcaption></figcaption></figure>

#### Excel equivalent

[LOG](https://support.microsoft.com/en-us/office/log-function-4e82f196-1ca9-4747-8fb0-6c4a3abb3280)


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