---
title: "How Performance scores are calculated"
date: "2021-12-06T07:55:40+00:00"
summary: "Discover how Acquia Web Governance uses Google Lighthouse to determine your Performance scores."
image:
type: "page"
url: "/web-governance/how-performance-scores-are-calculated"
id: "fc5548bb-27c1-4017-9850-3567ca5fc2b4"
---

Acquia Web Governance uses Google Lighthouse, a tool that delivers data to the Performance module with a performance weighting system. Weighting of the different metrics in the calculation of the overall score can change with any upgrade. You may experience a change in your Performance Score as a result of any Google Lighthouse upgrade.

Note

Some of the scores that are calculated are not visible in the report but are calculated into the score in the background.

The History Center displays an indication when the version changes, in order to help you understand why the Performance score shows a sudden jump.

For more information on how the scores are calculated, visit:

*   [Lighthouse performance scoring](https://web.dev/performance-scoring/#weightings)
*   [Lighthouse scoring calculator](https://googlechrome.github.io/lighthouse/scorecalc/)

**2\. Excluding archived profiles from the Average Performance score**

In the History Center, Web Governance displays an _Average Performance score_ which is calculated as the average of all the Performance Scores of your pages. For example, if you run performance scans on six pages, the _Average Performance score_ is the average score of those six.

Archived profiles are disregarded from the _Average Performance score_ calculation. This makes the score more accurate. This only affects your score if you have archived Performance profiles on your account.

Additional information from Google Lighthouse
---------------------------------------------

How the Performance score is weighted:

The Performance score is a weighted average of the metric scores. Metrics that are more heavily weighted have a greater effect on your overall performance score.

The metric scores are not visible in the report but are calculated in the background.

The weightings are chosen to provide a balanced representation of your perception of performance.

![A screenshot of Google Lighthouse scoring calculator web app](https://acquia.widen.net/content/f180b6ae-c302-4947-9256-ce6c4005c2fe/web/Mon_Performance_Google_Lighthouse_Scoring_Calculator.png)

Explore scoring with the [Lighthouse scoring calculator](https://googlechrome.github.io/lighthouse/scorecalc/).

How metric scores are determined
--------------------------------

When the performance metrics are gathered, (mostly reported in milliseconds), Lighthouse converts each raw metric value into a metric score from 0 to 100 by looking where the metric value falls on its Lighthouse scoring distribution.

Additional Resources
--------------------

For more information, visit:

*   [Performance User Guide](/en/articles/5703632-performance)
*   [Performance Update with new Google Web Vitals](/node/59306)