k6/metrics on Grafana Labs

Counter

Mon, 21 Sep 2026 15:16:28 +0000

Counter

Counter is an object for representing a custom cumulative counter metric. It’s one of the four metric types.

Parameter	Type	Description
`name`	string	The name of the custom metric.

Method	Description
Counter.add(value, [tags])	Add a value to the counter metric.

Counter usage in Thresholds

When Counter is used in a threshold expression, the variable must be called count or rate (lower case). For example:

count >= 200 // value of the counter must be larger or equal to 200
count < 10 // less than 10.

Examples

import { Counter } from 'k6/metrics';

const myCounter = new Counter('my_counter');

export default function () {
  myCounter.add(1);
  myCounter.add(2, { tag1: 'myValue', tag2: 'myValue2' });
}

import http from 'k6/http';
import { Counter } from 'k6/metrics';

const CounterErrors = new Counter('Errors');

export const options = { thresholds: { Errors: ['count<100'] } };

export default function () {
  const res = http.get('https://quickpizza.grafana.com/api/json?name=Bert');
  const contentOK = res.json('name') === 'Bert';
  CounterErrors.add(!contentOK);
}

import { Counter } from 'k6/metrics';
import { sleep } from 'k6';
import http from 'k6/http';

const allErrors = new Counter('error_counter');

export const options = {
  vus: 1,
  duration: '1m',
  thresholds: {
    'error_counter': [
      'count < 10', // 10 or fewer total errors are tolerated
    ],
    'error_counter{errorType:authError}': [
      // Threshold on a sub-metric (tagged values)
      'count <= 2', // max 2 authentication errors are tolerated
    ],
  },
};

export default function () {
  const auth_resp = http.post('https://quickpizza.grafana.com/api/users/token/login', {
    username: 'default',
    password: 'supersecure',
  });

  if (auth_resp.status >= 400) {
    allErrors.add(1, { errorType: 'authError' }); // tagged value creates submetric (useful for making thresholds specific)
  }

  const other_resp = http.get('https://quickpizza.grafana.com/api/json');
  if (other_resp.status >= 400) {
    allErrors.add(1); // untagged value
  }

  sleep(1);
}

Gauge

Mon, 21 Sep 2026 15:16:28 +0000

Gauge

Gauge is an object for representing a custom metric holding only the latest value added. It’s one of the four metric types.

Parameter	Type	Description
`name`	string	The name of the custom metric.
`isTime`	boolean	A boolean indicating whether the values added to the metric are time values or just untyped values.

Method	Description
Gauge.add(value, [tags])	Add a value to the gauge metric. Only the latest value added will be kept.

Gauge usage in Thresholds

When gauge is used in a threshold expression, the variable must be called value (lower case). For example:

value < 200
value > 1

Examples

import { Gauge } from 'k6/metrics';

const myGauge = new Gauge('my_gauge');

export default function () {
  myGauge.add(3);
  myGauge.add(1);
  myGauge.add(2, { tag1: 'value', tag2: 'value2' });
}

import http from 'k6/http';
import { sleep } from 'k6';
import { Gauge } from 'k6/metrics';

const GaugeContentSize = new Gauge('ContentSize');

export const options = {
  thresholds: {
    ContentSize: ['value<4000'],
  },
};

export default function () {
  const res = http.get('https://quickpizza.grafana.com');
  GaugeContentSize.add(res.body.length);
  sleep(1);
}

Rate

Mon, 21 Sep 2026 15:16:28 +0000

Rate

Rate is an object for representing a custom metric keeping track of the percentage of added values that are non-zero. It’s one of the four metric types.

Parameter	Type	Description
`name`	string	The name of the custom metric.

Method	Description
Rate.add(value, [tags])	Add a value to the rate metric.

Rate usage in Thresholds

When Rate is used in a threshold expression, the variable must be called rate (lower case). For example:

rate < 0.1 // less than 10%
rate >= 0.9 // more or equal to 90%

The value of the rate variable ranges between 0.00 and 1.00.

Examples

import { Rate } from 'k6/metrics';

const myRate = new Rate('my_rate');

export default function () {
  myRate.add(true);
  myRate.add(false);
  myRate.add(1);
  myRate.add(0, { tag1: 'value', tag2: 'value2' });
}

import { Rate } from 'k6/metrics';
import { sleep } from 'k6';
import http from 'k6/http';

const errorRate = new Rate('errorRate');

export const options = {
  vus: 1,
  duration: '5m',
  thresholds: {
    errorRate: [
      // more than 10% of errors will abort the test
      { threshold: 'rate < 0.1', abortOnFail: true, delayAbortEval: '1m' },
    ],
  },
};

export default function () {
  const resp = http.get('https://quickpizza.grafana.com');

  errorRate.add(resp.status >= 400);

  sleep(1);
}

Trend

Mon, 21 Sep 2026 15:16:28 +0000

Trend

Trend is an object for representing a custom metric that allows for calculating different statistics on the added values (min, max, average or percentiles). It’s one of the four metric types.

Parameter	Type	Description
`name`	string	The name of the custom metric.
`isTime`	boolean	A boolean indicating whether the values added to the metric are time values or just untyped values.

Method	Description
Trend.add(value, [tags])	Add a value to the trend metric.

Trend usage in Thresholds

When Trend is used in a threshold expression, there are a range of variables that can be used.

avg for average
min for minimum
max for maximum
med for median
p(N) for specific percentile. N is a number between 0.0 and 100.0 meaning the percentile value to look at, e.g. p(99.99) means the 99.99th percentile.

The unit of these variables and functions are all in milliseconds.

Example threshold expressions:

p(95) < 400 // 95% of requests must finish below 400ms
p(99) < 1000 // 99% of requests must finish within 1s.
p(50) < 200 // half of requests must finish within 200ms.
max < 3000 // the slowest request must finish within 3s.

⚠️ Don’t use min and max in thresholds

We don’t recommend using min and max for specifying thresholds because these values represent outliers. Use percentiles instead.

Examples

import { Trend } from 'k6/metrics';

const myTrend = new Trend('my_trend');

export default function () {
  myTrend.add(1);
  myTrend.add(2, { tag1: 'value', tag2: 'value2' });
}

import { Trend } from 'k6/metrics';
import { sleep } from 'k6';
import http from 'k6/http';

const serverWaitingTimeOnLogin = new Trend('serverWaitingTimeOnLogin', true);

export const options = {
  vus: 1,
  duration: '1m',
  thresholds: {
    serverWaitingTimeOnLogin: ['p(95) < 200'],
  },
};

export default function () {
  const resp = http.post('https://quickpizza.grafana.com/api/users/token/login', {
    username: 'default',
    password: 'supersecure',
  });

  serverWaitingTimeOnLogin.add(resp.timings.waiting);
  sleep(1);
}

k6/metrics on Grafana Labs

Counter

Counter

Counter usage in Thresholds

Examples

Gauge

Gauge

Gauge usage in Thresholds

Examples

Rate

Rate

Rate usage in Thresholds

Examples

Trend

Trend

Trend usage in Thresholds

Example threshold expressions:

⚠️ Don’t use min and max in thresholds

Examples

⚠️ Don’t use `min` and `max` in thresholds