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The k6/metrics module provides custom metric types for tracking and aggregating performance data in your tests.

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Import

import { Counter, Gauge, Rate, Trend } from 'k6/metrics';

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Metric Types

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Counter

Counter is a cumulative metric that only increases. Use it to count events, errors, or accumulate values.
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name
string
required
The name of the custom metric.
Methods:
  • add(value, [tags]) - Add a value to the counter
import { Counter } from 'k6/metrics';

const myCounter = new Counter('my_counter');

export default function () {
  myCounter.add(1);
  myCounter.add(2, { tag1: 'myValue', tag2: 'myValue2' });
}
Threshold variables:
  • count - The total count value
  • rate - The rate of the counter
Examples: count >= 200, count < 10

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Gauge

Gauge holds only the latest value added. Use it for tracking current state or the most recent measurement.
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name
string
required
The name of the custom metric.
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isTime
boolean
Indicates whether the values are time values or untyped values.
Methods:
  • add(value, [tags]) - Add a value to the gauge (only the latest value is kept)
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' });
}
Threshold variable:
  • value - The current gauge value
Examples: value < 200, value > 1

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Rate

Rate tracks the percentage of added values that are non-zero. Use it for calculating success/failure rates.
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name
string
required
The name of the custom metric.
Methods:
  • add(value, [tags]) - Add a boolean or numeric value (non-zero counts as true)
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' });
}
Threshold variable:
  • rate - The rate value between 0.00 and 1.00
Examples: rate < 0.1 (less than 10%), rate >= 0.9 (90% or more)

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Trend

Trend calculates statistics on added values (min, max, average, percentiles). Use it for timing measurements and performance analysis.
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name
string
required
The name of the custom metric.
​
isTime
boolean
Indicates whether the values are time values (in milliseconds) or untyped values.
Methods:
  • add(value, [tags]) - Add a value to the trend
import { Trend } from 'k6/metrics';

const myTrend = new Trend('my_trend');

export default function () {
  myTrend.add(1);
  myTrend.add(2, { tag1: 'value', tag2: 'value2' });
}
Threshold variables:
  • avg - Average value
  • min - Minimum value (not recommended for thresholds)
  • max - Maximum value (not recommended for thresholds)
  • med - Median value
  • p(N) - Specific percentile (N between 0.0 and 100.0)
Examples:
  • p(95) < 400 - 95% of requests finish below 400ms
  • p(99) < 1000 - 99% of requests finish within 1s
  • p(50) < 200 - Half of requests finish within 200ms
  • max < 3000 - Slowest request finishes within 3s
Don’t use min and max for thresholds as they represent outliers. Use percentiles instead.

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