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GTmetrix: How To Use The Speed Test Tool

Looking to improve your site's performance? Learn how to use GTmetrix to uncover different factors affecting your online visibility.

GTmetrix: How To Use The Speed Test Tool

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

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

Today, we will go over GTmetrix, the speed test tool.

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

What Is GTmetrix?

GTmetrix is a web-based tool that provides an analysis of website speed.

It will analyze a site’s load time, size, and requests happening, and then generate a score with recommendations to improve it.

This tool can be used by site owners, engineers, SEO pros, and others to measure their site’s performance and look for room for improvement.

GTmetrix homepage interfaceScreenshot from, February 2023

How To Use GTmetrix

The GTmetrix tool exists 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 edit the location and browser type.

To use GTmetrix, plug your URL into the website.

GTmetrix interface Screenshot from, February 2023

Once the report is complete, you can review the metrics provided (we will go into more detail about the meaning of those below).

You will receive an overview of the GTmetrix Grade, Web Vitals, and a summary that shows the speed visualizations.

The speed visualization is a great way to see what your website looks like as it loads, layered in with the metrics overlayed.

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

It also provides the level of impact, which is helpful for prioritization.

Although these are the first available after running the test, GTmetrix recommends you focus on specific audits found in the Structure tab.

GTmetrix Summary pageScreenshot from, February 2023

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

Performance Tab

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

Structure Tab

This is the section that GTmetrix suggests you start with. This section outlines the tool’s various audits and the impact the items have.

There is detailed information available 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 explaining in more detail how this issue impacts performance, how it works, and how to avoid it.

Here’s what’s really useful: it provides what level of experience is required to make these optimizations.

GTmetrix optimization recommendation boxScreenshot from, February 2023

Waterfall Tab

This tab illustrates a waterfall chart and the details of each action in a waterfall approach.

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

Gtmetrix waterfall report exampleScreenshot from, February 2023

You can hover over the resource row and see a detailed breakdown of why the resource takes too long to load.

Screenshot 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 solved by using CDN for resources.

Video Tab

This tab provides the option to record a video of a page load and use it to pinpoint different issues with the page.

You will need an account to leverage this tool.

History Tab

Here you can view graphs that display changes over time to your page metrics like page sizes, time to interact, and scores.

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

Gtmetrix's history tabScreenshot from, February 2023

What GTmetrix Measurement Means

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

GTmetrix Grade Overview

GTmetrix Grade

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

The grade is determined by considering the users’ load time and the website’s architectural design.

A fast-loading website that is well-architected for performance is likely to receive a higher grade, while a slow site with longer load times or poor architectural design may receive a lower grade.

Performance Score

The performance score, as stated on the GTmetrix website, can be compared to a Lighthouse Performance Score.

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


The structure rating combines GTmetrix’s proprietary assessment of its custom audits with the Lighthouse assessment.

The score represents how well the site is architected for performance.

GTmetrix Grade visualScreenshot from, February 2023

Web Vitals

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

Largest Contentful Paint (LCP)

LCP refers to the time it takes for the most significant element on your website page to load where the 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’s load responsiveness to user input.

It is meant to measure the amount of time that prevented the user from interacting.

This replaced First Input Delay (FID) that was used in PageSpeed Insights.

Cumulative Layout Shift (CLS)

CLS is the metric that measures unexpected shifting of page elements while the page is loading.

This metric is also used in Google’s Web Vitals.

This is meant to rate the stability of a webpage.

Web Vitals DashboardScreenshot from, February 2023


GTmetrix offers valuable insights and information to enhance the performance of your website.

It acts as a comprehensive tool to assess the well-being of your site and uncover factors affecting your search engine visibility.

By utilizing GTmetrix, you can take proactive steps to optimize and improve your online presence.

More Resources:

Featured Image: Billion Photos/Shutterstock

Category Tools Technical SEO
Tessa Nadik Sr. Director of Product Management, SEO & Content Strategy at Kelly Blue Book & Autotrader

Tessa Nadik leads the SEO and Content Team at Kelley Blue Book and Autotrader as the Sr. Director for Cox ...

GTmetrix: How To Use The Speed Test Tool

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