---
title: date.truncate() function
description: >
  `date.truncate()` returns a time truncated to the specified duration unit.
menu:
  flux_v0_ref:
    name: date.truncate
    parent: date
    identifier: date/truncate
weight: 101
---

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`date.truncate()` returns a time truncated to the specified duration unit.



##### Function type signature

```js
(t: A, unit: duration, ?location: {zone: string, offset: duration}) => time where A: Timeable
```

{{% caption %}}
For more information, see [Function type signatures](/flux/v0/function-type-signatures/).
{{% /caption %}}

## Parameters

### t
({{< req >}})
Time to operate on.

Use an absolute time, relative duration, or integer.
Durations are relative to `now()`.

### unit
({{< req >}})
Unit of time to truncate to.

Only use 1 and the unit of time to specify the unit.
For example: `1s`, `1m`, `1h`.

### location

Location used to determine timezone.
Default is the `location` option.




## Examples

- [Truncate time values](#truncate-time-values)
- [Truncate time values using relative durations](#truncate-time-values-using-relative-durations)
- [Query data from this year](#query-data-from-this-year)
- [Query data from this calendar month](#query-data-from-this-calendar-month)

### Truncate time values

```js
import "date"
import "timezone"

option location = timezone.location(name: "Europe/Madrid")

date.truncate(t: 2019-06-03T13:59:01Z, unit: 1s)

// Returns 2019-06-03T13:59:01.000000000Z
date.truncate(t: 2019-06-03T13:59:01Z, unit: 1m)

// Returns 2019-06-03T13:59:00.000000000Z
date.truncate(t: 2019-06-03T13:59:01Z, unit: 1h)

// Returns 2019-06-03T13:00:00.000000000Z
date.truncate(t: 2019-06-03T13:59:01Z, unit: 1d)

// Returns 2019-06-02T22:00:00.000000000Z
date.truncate(t: 2019-06-03T13:59:01Z, unit: 1mo)

// Returns 2019-05-31T22:00:00.000000000Z
date.truncate(t: 2019-06-03T13:59:01Z, unit: 1y)// Returns 2018-12-31T23:00:00.000000000Z


```


### Truncate time values using relative durations

```js
import "date"

option now = () => 2020-01-01T00:00:30.5Z

date.truncate(t: -30s, unit: 1s)

// Returns 2019-12-31T23:59:30.000000000Z
date.truncate(t: -1m, unit: 1m)

// Returns 2019-12-31T23:59:00.000000000Z
date.truncate(t: -1h, unit: 1h)// Returns 2019-12-31T23:00:00.000000000Z


```


### Query data from this year

```js
import "date"

from(bucket: "example-bucket")
    |> range(start: date.truncate(t: now(), unit: 1y))

```


### Query data from this calendar month

```js
import "date"

from(bucket: "example-bucket")
    |> range(start: date.truncate(t: now(), unit: 1mo))

```