How Does the Lighthouse Test Impact Your SEO Efforts?

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September 9, 2022


In the early days of the internet, there was next to no focus on how well a page functioned in terms of speed, and although some SEO tactics were used, there was very little onus on website performance monitoring and no easy way to understand it.

This changed in November 2018, with the introduction of the Lighthouse test. Google began to realize that speed matters and brought out a variety of tools to help developers understand the performance of a page or site in a much more accessible way.

If you’re working on your website SEO, then you must understand what the google lighthouse test is and how it impacts your ranking ability. The better the score, the more chance your site has of ranking higher.

In this article, we tell you everything you need to know about your Lighthouse score and what it means for your site's SEO. Read on to find out what they are and how they can affect your rankability.

What Is The Lighthouse Test?

Google Lighthouse is an open-source program that gives you powerful insights into your website. Its main goal is to give you the analytics you need for improving SEO, speed, and anything else that will boost the quality of your web pages.

When you run a Google Lighthouse report on your site, it assesses and gives a score based on a range of criteria with the main goal of telling you how positive an experience a user will have on your site. It gives valuable hints as to what you can do to improve these metrics if the scores are low.

Because Google search results' main goal is to provide the best experience for its users, it will favor websites that have a high lighthouse score which is why paying attention to your Lighthouse score directly impacts your SEO efforts.

The Importance Of Website Performance Monitoring

Google's algorithm is constantly changing and evolving, and tactics and strategies that worked a few years ago are no longer relevant. It can be hard to predict exactly what Google’s algorithms are looking for; however, one thing that you can be certain of is the user experience.

All of the recent updates in the algorithms over the past few years have been geared toward the user experience or UX, which is usually referred to. Part of the UX is based on Web Vitals, which are now a ranking factor for Google, especially when it comes to mobile browsing. What this means is that if your site isn't set up for mobile first, is slow, and lacks security features, then it will equate to a poor user experience and a lesser chance of getting onto the top page of results.

Real User Monitoring

Real User Monitoring or RUM data falls under website performance monitoring. This is the field data based on the performance experienced by visitors o your site. This is what Google uses to determine if your site is passing the recommended Google Web Core vitals.

One way to check your RUM is by using the Google Chrome User Experience Report (CrUX) tool. This tool provides user experience metrics on how real-world Chrome users experience your site. This is just one way of using an analysis app to help boost your SEO effort.

Other Google RUM Tools

  • Search Console
  • PageSpeed Insights
  • Web-vitals JavaScript library

Lab Data Vs RUM Data

Both lab data or synthetic data and RUM data are important for improving your chances of ranking high in search results. The difference is that lab data is collected from a controlled environment, whereas RUM data is based on actual users.

RUM data can vary greatly thanks to some users having a fast experience, and other UX can be slow because it’s based on network conditions, the device they are using, or location. The results you get in Lighthouse are based on synthetic data, as opposed to RUM data.

How Does Google Lighthouse Score Help?

One of the main ways that Google Lighthouse benefits your SEO efforts is that you can see a bit-by-bit breakdown of exactly how much users would potentially enjoy the experience of your site. It works as a customer-eye-view and highlights what things you’re doing well and what aspects need attention. It will even give you a list of things that you need to work on to improve your score.

Scoring Metrics Of Google Lighthouse

The score you will see on Lighthouse is based on a 1-100 grading system, with 1 being a poor score and 100 being an excellent score. There are five overall categories that you will see a score for:

  1. Performance
    This includes aspects such as the load time. The load time is broken down into six different metrics that we’ll go into later. It also covered the overall quality of the user experience and how well your site answers the problem a user has searched for.

  2. Accessibility
    Lighthouse evaluates how well your site complies with web accessibility best practices. This includes the importance of contrast on the tested page, and how easy words are to read - for example, pink writing a red background would be difficult to read. It also refers to the use of alt tags on images that describe the image. Essentially this score relates to how effectively are visually impaired or blind users able to navigate your site with text-to-speech tools if necessary.

  3. Best Practices
    Google checks that your site follows its best practices. This includes site security, such as the use of HTTPS. It also takes into account the absence of page errors and attributes of images. Some of these metrics also link back to page load time and the resolution and size of images.

  4. SEO
    To tick the SEO box, this metric covers things like meta tags and index pages so that Google can crawl any internal and external links on your site. SEO is a whole category in itself, so Lighthouse only scratches the surface of everything involved here. It’s best to do a separate SEO audit in addition to a Lighthouse Test.

  5. Progressive Web App
    This takes into account everything that makes up your site, including CSS and Javascript, and how well these work on web browsing, mobile brows, and apps. Progressive Web Apps or PWAs are a hybrid of mobile apps and web pages and help to make sites easier to access on a mobile device.

How Does Lighthouse Calculate Its Performance Score?

After you’ve run a Lighthouse Test on your site, you’ll be presented with the results and key information to improve anywhere you may be failing. There’s a bit of jargon to get your head around, which we’ll break down now in this section.

Largest Contentful Paint

The Largest Contentful Paint of the LCP is the Core Web Vitals that evaluates the display speed of your site. It’s based on the largest element on a web page, which could be an image, video, or text, depending on how your page is set it. The result here accounts for 25% of the Lighthouse score, so if it’s showing up in the red, you need to do something about raising this score as it will have a big impact on the overall Lighthouse report.

Cumulative Layout Shift

The Cumulative Layout Shift, or the CLS, also refers to another Core Web Vitals. This metric refers to the visual stability of your web page. Although important, it only equates to 5% of the overall Lighthouse score.

Total Blocking Time

The Total Blocking Time or TBT refers to the times that a page cannot respond to interactions. It’s based on data taken from Long Tasks in the Main Thread, which refers to anything that needs more than 50 ms to be executed. It accounts for 25% of your Lighthouse score, so again, this is flagging up in the red; you should prioritize doing something about it.

First Contentful Paint

The FCP or First Contentful Pain indicates the time in which the first element on your site is rendered by the browser. It equates to 15 of your overall Lighthouse score.

Speed Index

The Speed Index evaluates how quickly things load in the viewport above the fold. This is what can be seen on a page without scrolling. This accounts for 15% of the overall Lighthouse score.

Time To Interactive

The Time to Interactive metric or TTI refers to how long it takes for a page to become interactive without latency. Ideally, this wants to be at around 2 - 3 seconds. The TTI equates to 15% of the overall Lighthouse score.

Each of these sections will be color coded with a traffic light system and a drop-down menu of things you can do to improve the score.

Are You Ready to Start Using Google Lighthouse?

Because Google Lighthouse test is an open-source app, it means that it's freely accessible to everyone. Anyone can run an analyst on their site and see where their pitfalls are. However, when you get into the nitty-gritty of understanding the numbers that come back, this is when it can get confusing.

Loado is a real-user monitoring tool that offers user analytics features. With RUM, you can monitor performance from the perspective of real users. You'll be able to track metrics from real data sets and get relevant insights into how users are actually interacting with your site. You'll be able to see what devices they're using, what regions they're in, and more. This will give you much more accurate insights than you could ever get from synthetic testing or batch testing. Feel free to try our service, we have free trial and no credit card is required.

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