---
title: prometheus.histogramQuantile() function
description: >
  `prometheus.histogramQuantile()` calculates a quantile on a set of Prometheus histogram values.
menu:
  flux_v0_ref:
    name: prometheus.histogramQuantile
    parent: experimental/prometheus
    identifier: experimental/prometheus/histogramQuantile
weight: 201
flux/v0/tags: [transformations, aggregates, prometheus]
---

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`prometheus.histogramQuantile()` calculates a quantile on a set of Prometheus histogram values.

This function supports [Prometheus metric parsing formats](/influxdb/v2/reference/prometheus-metrics/)
used by `prometheus.scrape()`, the Telegraf `promtheus` input plugin, and
InfluxDB scrapers available in InfluxDB OSS.

##### Function type signature

```js
(<-tables: stream[{B with le: D, _field: C}], quantile: float, ?metricVersion: A, ?onNonmonotonic: string) => stream[E] where A: Equatable, C: Equatable, E: Record
```

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

## Parameters

### quantile
({{< req >}})
Quantile to compute. Must be a float value between 0.0 and 1.0.



### metricVersion

[Prometheus metric parsing format](/influxdb/v2/reference/prometheus-metrics/)
used to parse queried Prometheus data.
Available versions are `1` and `2`.
Default is `2`.



### tables

Input data. Default is piped-forward data (`<-`).



### onNonmonotonic

Describes behavior when counts are not monotonically increasing
when sorted by upper bound. Default is `error`.

**Supported values**:
- **error**: Produce an error.
- **force**: Force bin counts to be monotonic by adding to each bin such that it
is equal to the next smaller bin.
- **drop**: When a nonmonotonic table is encountered, produce no output.


## Examples

- [Compute the 0.99 quantile of a Prometheus histogram](#compute-the-099-quantile-of-a-prometheus-histogram)
- [Compute the 0.99 quantile of a Prometheus histogram parsed with metric version 1](#compute-the-099-quantile-of-a-prometheus-histogram-parsed-with-metric-version-1)

### Compute the 0.99 quantile of a Prometheus histogram

```js
import "experimental/prometheus"

prometheus.scrape(url: "http://localhost:8086/metrics")
    |> filter(fn: (r) => r._measurement == "prometheus")
    |> filter(fn: (r) => r._field == "qc_all_duration_seconds")
    |> prometheus.histogramQuantile(quantile: 0.99)

```


### Compute the 0.99 quantile of a Prometheus histogram parsed with metric version 1

```js
import "experimental/prometheus"

from(bucket: "example-bucket")
    |> range(start: -1h)
    |> filter(fn: (r) => r._measurement == "qc_all_duration_seconds")
    |> prometheus.histogramQuantile(quantile: 0.99, metricVersion: 1)

```