# Reference > Extensions > Apdex

# `apdex` - Calculate and report Apdex scores

[Apdex](https://en.wikipedia.org/wiki/Apdex) is an open standard for turning response time measurements into simple scores
that reflect user satisfaction with the service. With the `apdex` plugin Artillery can track and visualize those scores for you.

> **Info:** This plugin is only compatible with the `http` engine.

## Usage

Enable Apdex scoring by loading the official `apdex` plugin in the config section of your test definition:

```yaml
config:
  plugins:
    apdex: {}
```

You can then run your load test as normal.

The plugin will report [3 additional metrics](#metrics-reported-by-the-plugin) for each test. The overall Apdex score will be printed at the end of the test run.

## Plugin Configuration

The default threshold value is `500` (in milliseconds). The value may be customized. For example to reduce the value to `200`:

```yaml
config:
  plugins:
    apdex:
      threshold: 200
```

## Metrics reported by the plugin

In addition to the [default metrics](../reported-metrics#metrics-reported-by-artillery) reported by Artillery and your chosen engine(s), this plugin reports the following additional metrics:

| Metric             | Type                                       | Description                                                                          |
| ------------------ | ------------------------------------------ | ------------------------------------------------------------------------------------ |
| `apdex.satisfied`  | Counter (count) | Number of requests that have been served faster than the predefined threshold value. |
| `apdex.tolerated`  | Counter (count) | Number of requests that are classified as `tolerated`.                               |
| `apdex.frustrated` | Counter (count) | Number of requests that were too slow.                                               |