GTmetrix: How To Use The Speed Test Tool

With so many tools and applications available to our industry, it is impossible to know every single one of them.

There are questions about what they do, how much they cost, what they’re used for, and many others that bug us when we’re looking for a tool to help us solve problems.

Today, we are going to go through GTmetrix, the speed test tool.

We’ll review the uses, how to use the tool, and what to do with the output.

What is GTmetrix?

GTmetrix It is a web based tool that provides website speed analysis.

It will analyze the site’s load time, size, and occurrence requests, and then generate a score with recommendations for optimization.

This tool can be used by website owners, engineers, SEO professionals, and others to measure the performance of their sites and look for room for improvement.

Screenshot from, February 2023

How to use GTmetrix

GTmetrix is ​​located on a website that you can access online.

You don’t need an account to get started – but you will need one if you want to be able to modify the site and browser type.

To use GTmetrix, enter your URL into the website.

GTmetrix interface Screenshot from, February 2023

Once the report is complete, you can review the metrics provided (we’ll go into more detail on what those metrics mean below).

You’ll receive an overview of GTmetrix Grade, Web Vitals, and a summary with velocity visualizations.

Velocity visualization is a great way to see what your website looks like as it loads, with layers of metrics overlaid.

At the bottom, the main issues are noted and broken down by total topics: First Contentful Paint (FCP), Largest Contentful Paint (LCP), Total Blocking Time (TBT), and Compulsive Layout Shift (CLS).

It also provides an impact level, which is useful for setting priorities.

Although these are the first ones available after you run the test, GTmetrix recommends focusing on specific checks found in the Structure tab.

GTmetrix summary pageScreenshot from, February 2023

Let’s take a look at each of the different tabs within GTmetrix, and how they are useful.

Performance tab

The Performance tab provides insight into various performance-based metrics, including things like FCP, Speed ​​Index, CLS, and other browser-specific metrics.

Structure tab

This is the section GTmetrix suggests you start with. This section describes the various audits of the tool and the effect of the items.

Detailed information is provided in each of these audits that shows what needs to be corrected.

Much of this information is technical, and if you need a better understanding, GTmetrix provides a “Learn how to improve this” button that takes you to a wiki that explains in more detail how this issue affects performance, how it works, and how to avoid it.

Here’s what’s really useful: It provides the level of expertise required to make these improvements.

GTmetrix Improvement Recommendation FundScreenshot from, February 2023

Waterfall tab

This tab shows a waterfall diagram and details each action in the waterfall policy.

Here, you should pay attention to resources that take a long time to load.

Example of a Gtmetrix waterfall reportScreenshot from, February 2023

You can hover over the resource row and see a detailed analysis of why the resource is taking too long to load.

GTmetrix: How to use the speed test toolScreenshot from, February 2023

In this example we see that for the server it took about 700ms to respond – which may indicate server issues that can be resolved with a resource CDN.

Video tab

This tab provides an option to record a video of the page loading and use it to identify various issues with the page.

You will need an account to take advantage of this tool.

History tab

Here you can view graphs that show changes over time to your page metrics such as page sizes, interaction time, and hits.

This is a great way to measure your progress over time.

Gtmetrix history tabScreenshot from, February 2023

What does GTmetrix mean?

As we discussed above, GTmetrix produces an overall score as its output, but what it measures is also essential.

GTmetrix grade overview

GTmetrix grade

This is the metric that helps you understand the overall performance of your website.

The score is determined by taking into account users’ loading time and the site’s architectural design.

A fast-loading website well designed for performance is likely to receive a higher score, while a slow site with longer loading times or poor architecture may receive a lower score.

performance points

The performance score, as listed on the GTmetrix website, can be compared with the Lighthouse Performance Score.

This is useful information for anyone who wants to understand the metric and its relationship to other performance metrics.


Chassis Rating combines GTmetrix’s proprietary rating for its custom audits with a Lighthouse rating.

The score represents how well the site is designed to perform.

GTmetrix Grade OpticalScreenshot from, February 2023

web animation

This section highlights the metrics that Google uses to determine if a website is creating what it refers to as a “pleasant experience”.

Largest Content Coating (LCP)

LCP refers to the time it takes to load the most important element of your website page where a user can see it.

A good user experience would be 1.2 seconds or less.

Total blocking time (TBT)

TBT is a Lighthouse metric created to measure your website load response to user input.

Its purpose is to measure the amount of time the user has been prevented from interacting.

This replaced the first input delay (FID) that was used in PageSpeed ​​Insights.

Cumulative Planning Shift (CLS)

CLS is the metric that measures unexpected change of page elements during page load.

This metric is also used in Google Web Essentials.

This is intended to assess the stability of a web page.

Dashboard Screenshot from, February 2023


GTmetrix provides valuable insights and information to improve your website’s performance.

It serves as a comprehensive tool for assessing your site’s well-being and uncovering factors that affect your search engine visibility.

By using GTmetrix, you can take proactive steps to enhance and improve your online presence.

More resources:

  • 17 Free SEO Tools for Website Audits
  • Basic web essentials: Google’s top 3 metrics for evaluating user experience
  • Basic Web Basics: A Complete Guide

Featured image: Billion Images / Shutterstock

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