# pct

Calculates, at each timestamp, the nth percentile of values of the input series for each time interval. If grouping is specified, it calculates the specified percentile for each group.

### pct syntax

`pct(DOUBLE) [by FIELD [, FIELD, ...]] `

Where `DOUBLE`

is floating point number between 0.0 and 100.0, both inclusive.

### pct examples

#### Return the 95th percentile of all input time series

This query calculates a single time series, where each plotted value is the 99.9th percentile of the `MemoryUsed`

metric of the input time series for a timeslice.

`metric=MemoryUsed | pct(99.9)`

#### Return time series with average metric value in 95th percentile by a field

This query is similar to the previous but it calculates the percentile of the `MemoryUsed `

metric by a metric field, in this case, `node`

. The query returns a time series for each node; each plotted point in a time series corresponds to the 99.9th percentile of all of the input time series with that `node`

value, for a timeslice.

`metric=MemoryUsed | pct(99.9) by node`