---
title: Fill null values in data
description: Use the fill() function to replace null values.
url: https://docs.influxdata.com/enterprise_influxdb/v1/flux/guides/fill/
estimated_tokens: 1553
product: InfluxDB Enterprise v1
version: v1
---

# Fill null values in data

Use the [`fill()` function](/flux/v0/stdlib/universe/fill/) to replace *null* values with:

-   [the previous non-null value](#fill-with-the-previous-value)
-   [a specified value](#fill-with-a-specified-value)

```js
data
    |> fill(usePrevious: true)

// OR

data
    |> fill(value: 0.0)
```

#### Fill empty windows of time

The `fill()` function **does not** fill empty windows of time. It only replaces *null* values in existing data. Filling empty windows of time requires time interpolation *(see [influxdata/flux#2428](https://github.com/influxdata/flux/issues/2428))*.

## Fill with the previous value

To fill *null* values with the previous **non-null** value, set the `usePrevious` parameter to `true`.

Values remain *null* if there is no previous non-null value in the table.

```js
data
    |> fill(usePrevious: true)
```

**Given the following input:**

| _time | _value |
| --- | --- |
| 2020-01-01T00:01:00Z | null |
| 2020-01-01T00:02:00Z | 0.8 |
| 2020-01-01T00:03:00Z | null |
| 2020-01-01T00:04:00Z | null |
| 2020-01-01T00:05:00Z | 1.4 |

**`fill(usePrevious: true)` returns:**

| _time | _value |
| --- | --- |
| 2020-01-01T00:01:00Z | null |
| 2020-01-01T00:02:00Z | 0.8 |
| 2020-01-01T00:03:00Z | 0.8 |
| 2020-01-01T00:04:00Z | 0.8 |
| 2020-01-01T00:05:00Z | 1.4 |

## Fill with a specified value

To fill *null* values with a specified value, use the `value` parameter to specify the fill value. *The fill value must match the [data type](/flux/v0/language/types/#basic-types) of the [column](/flux/v0/stdlib/universe/fill/#column).*

```js
data
    |> fill(value: 0.0)
```

**Given the following input:**

| _time | _value |
| --- | --- |
| 2020-01-01T00:01:00Z | null |
| 2020-01-01T00:02:00Z | 0.8 |
| 2020-01-01T00:03:00Z | null |
| 2020-01-01T00:04:00Z | null |
| 2020-01-01T00:05:00Z | 1.4 |

**`fill(value: 0.0)` returns:**

| _time | _value |
| --- | --- |
| 2020-01-01T00:01:00Z | 0.0 |
| 2020-01-01T00:02:00Z | 0.8 |
| 2020-01-01T00:03:00Z | 0.0 |
| 2020-01-01T00:04:00Z | 0.0 |
| 2020-01-01T00:05:00Z | 1.4 |