---
title: 'PostgreSQL TRUNC() Function'
page_title: 'PostgreSQL TRUNC() Function: Truncating Numbers'
page_description: 'This tutorial shows you how to use the PostgreSQL TRUNC() function to truncate numbers to the specified decimal places.'
prev_url: 'https://www.postgresqltutorial.com/postgresql-math-functions/postgresql-trunc/'
ogImage: '/postgresqltutorial/film-film_category-category-tables.png'
updatedOn: '2024-02-16T14:26:33+00:00'
enableTableOfContents: true
previousLink:
  title: 'PostgreSQL SIGN() Function'
  slug: 'postgresql-math-functions/postgresql-sign'
nextLink:
  title: 'PostgreSQL TRIM_SCALE() Function'
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---

The PostgreSQL `TRUNC()` function returns a number truncated to a whole number or truncated to the specified decimal places.

## Syntax

The following illustrates the syntax of the PostgreSQL `TRUNC()` function:

```css
TRUNC(number [, precision])
```

## Arguments

The `TRUNC()` function accepts two arguments.

**1\) `number`**

The `number` argument is a numeric value to be truncated

**2\) `precision`**

The `precision` argument is an integer that indicates the number of decimal places.

If the `precision` argument is a positive integer, the `TRUNC()` function truncates digits to the right of the decimal point.

In case the `precision` is a negative integer, the `TRUNC()` function replaces digits to the left of the decimal point.

The precision argument is optional. If you don’t specify it, it defaults to zero (0\). In other words, the `number` is truncated to a whole number.

## Return value

The PostgreSQL `TRUNC()` function returns the same [numeric data type](../postgresql-tutorial/postgresql-numeric) as the first argument if the second argument is not specified. Otherwise, the function returns a numeric value if both arguments are used.

## Examples

### 1\) Truncate to a whole number example

The following example uses the `TRUNC()` function to truncate a number to an integer:

```css
SELECT
    TRUNC(10.6);
```

The result is:

```css
10
```

### 2\) Truncate to the specified decimal place

The following statement truncates a number to 2 decimal places:

```
 SELECT
    TRUNC(
        1.234,
        2
    );
```

Here is the result:

```css
1.23
```

### 3\) Truncate numbers with a negative second argument example

Consider the following example:

```css
SELECT
    TRUNC(150.45,-2)
```

The second argument is \-2, therefore, the `TRUNC()` function replaced the digits to the left of the decimal point that resulting in:

```
100
```

### 4\) Truncate numbers returned by a query

See the following `film`, `film_category`, and `category` tables in the [sample database](../postgresql-getting-started/postgresql-sample-database):

![film film_category category tables](/postgresqltutorial/film-film_category-category-tables.png)The following statement calculates the average rental rate by film category:

```
SELECT
    NAME,
    TRUNC(AVG( rental_rate ),2)
FROM
    film
INNER JOIN film_category
        USING(film_id)
INNER JOIN category
        USING(category_id)
GROUP BY
    NAME
ORDER BY NAME;
```

In this example, we used the `TRUNC()` function to truncate the average rentals to two decimal places.

The following picture illustrates the result:

![PostgreSQL TRUNC example](/postgresqltutorial/PostgreSQL-TRUNC-example.png)
In this tutorial, you have learned how to use the PostgreSQL `TRUNC()` function to truncate numbers.