---
name: "log10"
section: "3"
platform: "linux"
package: "man-pages"
version: "6.19-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux", "freebsd"]
url: "https://new.carta.tech/log10"
---

# log10(3)

base-10 logarithmic function

## NAME

log10, log10f, log10l -  base-10 logarithmic function

## LIBRARY

Math library (*libm*, *-lm*)

## SYNOPSIS

```
#include <math.h>
```

**double log10(double** *x***);** **float log10f(float** *x***);** **long double log10l(long double** *x***);**

Feature Test Macro Requirements for glibc (see [**feature\_test\_macros**(7)](/feature_test_macros/7.md)):

**log10f**(), **log10l**():

```
    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
```

## DESCRIPTION

These functions return the base-10 logarithm of *x*.

## RETURN VALUE

On success, these functions return the base-10 logarithm of *x*.

For special cases, including where *x* is 0, 1, negative, infinity, or NaN, see [**log**(3)](/log/3.md).

## ERRORS

See [**math\_error**(7)](/math_error/7.md) for information on how to determine whether an error has occurred when calling these functions.

For a discussion of the errors that can occur for these functions, see [**log**(3)](/log/3.md).

## ATTRIBUTES

For an explanation of the terms used in this section, see [**attributes**(7)](/attributes/7.md).

| | | |
| --- | --- | --- |
| **Interface** | **Attribute** | **Value** |
| **log10**(), **log10f**(), **log10l**() | Thread safety | MT-Safe |

## STANDARDS

C11, POSIX.1-2008.

## HISTORY

C99, POSIX.1-2001.

The variant returning *double* also conforms to SVr4, 4.3BSD, C89.

## SEE ALSO

[**cbrt**(3)](/cbrt/3.md), [**clog10**(3)](/clog10/3.md), [**exp10**(3)](/exp10/3.md), [**log**(3)](/log/3.md), [**log2**(3)](/log2/3.md), [**sqrt**(3)](/sqrt/3.md)