Everything You Needed to Know About GTMetrix Speed Test Tool

In 2020, which strangely feels like forever ago now, GTmetrix, a popular website benchmarking site, updated their platform with the most significant change yet. They replaced PageSpeed/YSlow libraries with Lighthouse, an industry-standard web performance platform. The GTmetrix report has been entirely redesigned with the Lighthouse data and metrics in mind.


GTmetrix has also developed a new scoring system that includes the GTmetrix Grade and the Performance and Structure Scores. The new GTmetrix report gives you deeper insight into your site’s performance through new tabs and visualizations.

We’ll share all the latest updates to GTmetrix reports and then some in our blog, Everything You Wanted to Know About GTMetrix Reports.

Let’s get started!

What is GTmetrix?

GTmetrix is a website benchmarking tool created by Canadian company GT.net. It allows users to quickly see how fast their website is performing, what it’s doing well, and what it needs to improve. GTmetrix is the most widely used benchmarking tool online. HostPoco uses the device to assist customers in understanding their sites and making improvements.

gtmetrix tool

GTmetrix is easy to use and understand. It makes it ideal for both newbies as well as experienced developers. Companies such as IBM, HPE & Bayer Pharmaceuticals, Bayer Pharmaceuticals (Bayer Pharmaceuticals), T-Mobile, Nordstrom, and Thomson Reuters trust GTmetrix. It’s significant enough for them, so it’s excellent sufficient for us!

What is a Lighthouse?

Before we get into GTmetrix, let me briefly cover Lighthouse, the new technology that they use.

Google’s Lighthouse tool allows you to analyze web pages or web apps and gather performance metrics to help you tune your website or app to achieve the best possible performance. Lighthouse can be used against any website, public or private. It can perform audits of performance, accessibility, progressive apps, and other features.

Lighthouse can be run in Chrome’s DevTools with a command line or with Node module. It will simply ask for a URL to audit. It will then run a series test against the page and generate a report about how it performed. You can then use the test results for improvement. Every trial comes with a reference document that explains the importance of each item and provides suggestions for how to fix them.

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GTmetrix: Your first test

GTmetrix offers two types of accounts: premium and free. You can access the premium test locations and run more tests per week with the paid version.

You can get free access to the following servers by creating a GTmetrix account:

San Antonio, Texas, USA
Vancouver, Canada
Sao Paulo, Brazil
London, United Kingdom
Mumbai, India
Hong Kong
Sydney, NSW, Australia

You can access the following locations with a paid account:

San Francisco, California USA
Cheyenne, Wyoming USA
Chicago, Illinois, USA
Danville, Virginia, USA
Quebec City, Quebec, Canada
Stockholm, Sweden
Amsterdam, The Netherlands
Frankfurt, Germany
Paris, France
Dubai, United Arab Emirates
Johannesburg, South Africa
Chennai, India
Busan, South Korea
Tokyo, Japan

A premium account is valuable if your website attracts attention in a particular region.

We’ll use a free account for this blog. Let’s first look at how we can customize our test.

analyze performance of website

You have the option of configuring several options when running your test. Many of these options are extremely useful. Click the Analysis Options dropdown.

gtmetrix analysis options

Interpreting GTmetrix Results

GTmetrix reports are highly informative and detailed. Understanding them can be difficult. Let us help you understand the implications for your website/application.


Details about Grading and Scoring

Lighthouse’s scoring system is the basis of the GTmetrix Report’s scoring system. GTmetrix has modified and tweaked the testing to produce the results they want. The final result is the GTmetrix Grade.

What is the GTmetrix Grade

GTmetrix Grade, a weighted score, is derived using the Performance and Structure scores. These scores replace legacy reports’ PageSpeed and YSlow scores.


The GTmetrix Grade represents a weighted sum of the two new scores based on percentages:

The Performance Score is 70 percent of the total score.

The remaining 30% of the total score is the Structure Score.

GTmetrix Grade calculates using a simple formula. It currently assigns a 70/30 weighting to the Performance and Structure Scores.

This is the GTmetrix Grade’s current configuration. GTmetrix is constantly tweaking and updating its formulas, and they will continue to evolve. This new method has been in use since November 2020.

Breaking Down the Performance Score

The performance score will tell you how your site performs from a users perspective

If you are able to run the numbers The Performance Score is the Lighthouse Performance score as determined through the GTmetrix tests by using their browser, software and hardware and the choices you have specified (such as AdBlock and Connection Speeds and more..)

Let’s examine How the Performance Score is broken into pieces:

The Performance Score comprised up of 6 measures that are weighted according to the following:

The performance of loading comprises 55% of the total score. The score is broken into the following categories:

First Contentful Paint

15%. This metric determines how fast visitors are able to view the information on your website including pictures, text, or video.

Speed Index

15%. This is a measure of how quickly your website is visually completed beyond the fold.

Largest Contentful Paint

25%. This is a performance measure created for 2020 in the work of Lighthouse to measure the user experience that they perceive to be loading for users. It is also one of the metrics used by the Google’s Web Vitals, for reference.

Interactivity is 40% that makes up this scoring. The score is broken down as follows:

Time to Interactive

15%. This is a performance measure which measures a website’s responsiveness to load. It also helps in identifying situations when a webpage appears like an interactive site but isn’t.

Total Blocking Time

25%. This is an performance measure that comes from Lighthouse that was introduced in 2020. It is a measure of the total time that your website was blocked from input by users. It is also among the measures that make the Google’s Web Vitals, for reference.

Visual Stability is 5percent in this rating. The score is broken into the following categories:

Cumulative Layout Shift

5%. It is an performance measure that was introduced in 2020 by Lighthouse that evaluates the perceived stability of visuals on the page’s load, i.e. unintentional shifting of web components on the page while it loads. It is also an aspect of one the metrics that make the Google’s Web Vitals, for reference.

Every one of them is assessed and then calculated as a score. Then, it is it is compared to a threshold and the sum of the results together with the appropriate weighting forms the Performance Score. The results that are derived from the Performance Score are accessible on the”Performance Tab in GTmetrix. GTmetrix report.

complete gtmetrix performance

GTmetrix Performance Score vs Google PageSpeedInsights or Web.dev

Although Google’s PageSpeed Insights, webdev, and page speed Insights are powered by Lighthouse technology, they still use their hardware and testing methods to calculate your Performance Score. The Google score is different from GTmetrix’s because of a few key differences:

Geographical differences
Hardware differences.
Differences in the network
Google-Magic’s Other Products
Although the scores from Google’s tools should be comparable, they will not be directly comparable. It is important to understand why.

GTmetrix loads your page using an Unthrottled connection. Unless you specify otherwise, GTmetrix will use a real browser. Based on user needs, some of these options can be modified, including screen resolution, speed, and location.

PageSpeed Insights (webdev) launches performance tests using emulated and headless browsers. Network throttling is used to simulate page loads under different network conditions. These options cannot be changed, unlike GTmetrix testing.

Google Tools, PageSpeed Insights, and webdev all uses Lantern. This results in dramatically different page loading behavior, as well as different test results and performance scores.


GTmetrix’s latest version is the most complete yet. It has been completely redesigned to incorporate the new data from Lighthouse Testing, which will likely change how you assess the site’s performance.

You can open a ticket from your Lab, or chat with us to get some help optimizing your site for GTmetrix. Our Happiness Engineers will review your site and make recommendations.

We hope that this extensive coverage of GTmetrix reporting will help you understand what you see when you run a report. It’s not just geek talk.

We’d love to hear your thoughts in the comments.