---
title: now() function
description: >
  `now()` is a function option that, by default, returns the current system time.
menu:
  flux_v0_ref:
    name: now
    parent: universe
    identifier: universe/now
weight: 101
flux/v0/tags: [date/time]
introduced: 0.7.0
---

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`now()` is a function option that, by default, returns the current system time.

#### now() vs system.time()
`now()` returns the current system time (UTC). `now()` is cached at runtime,
so all executions of `now()` in a Flux script return the same time value.
`system.time()` returns the system time (UTC) at which `system.time()` is executed.
Each instance of `system.time()` in a Flux script returns a unique value.

##### Function type signature

```js
() => time
```

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


## Examples

- [Use the current UTC time as a query boundary](#use-the-current-utc-time-as-a-query-boundary)
- [Define a custom now time](#define-a-custom-now-time)

### Use the current UTC time as a query boundary

```js
data
    |> range(start: -10h, stop: now())

```


### Define a custom now time

```js
option now = () => 2022-01-01T00:00:00Z

```