# histogram quantile

The histogram_quantile operator calculates the φ-quantile (0 ≤ φ ≤ 1) from the buckets of a Prometheus histogram.

The `histogram_quantile`

operator calculates the φ-quantile (0 ≤ φ ≤ 1) from the buckets of a histogram. This operator is specific to the Prometheus Histogram data type and does not work with non-Prometheus histograms. It is equivalent to the PromQL histogram_quantile() operator.

### histogram_quantile syntax

`histogram_quantile(quantile)`

### histogram_quantile examples

`histogram_quantile(.99)`

`histogram_quantile(.5)`

The following PromQL query to measure the 99th quantile of the ` apiserver_request_latencies`

histogram:

`histogram_quantile(0.99, rate(apiserver_request_latencies_bucket{}[5m]))`

It would be written in Sumo as:

`metric=apiserver_request_latencies_bucket | quantize using max | delta | histogram_quantile(0.99)`