What Are Core Web Vitals and How Can You Check Them – A Simple Guide

What is Google’s Core Web Vitals update?

In early 2020, scuttlebutt (Navy and Marine jargon for gossip) began to appear on the internet regarding a Google update targeted at improving UX (user experience - how a user experiences and interacts with a web page). Not long after the gossip began, Google announced the addition of core web vitals as a ranking signal for search results. Core web vitals are universally applicable website metrics used to loosely gauge UX. Google rarely announces algorithm updates before they are released, so knowing what will become a ranking signal and how it will be measured is powerful information. In this article, we’ll briefly discuss the following:
  • What Google rankings are
  • What core web vitals are
  • How the new Google core algorithm update will impact rankings
  • How you can measure/evaluate your website’s core web vitals

What are Google Rankings

When we say “ranking(s)”, we’re referring to where your website appears on Google’s search engine results pages (SERPs) for queries related to your business. For example, let’s say you work as a plumber in Idaho and someone searches “plumbing services in Idaho”. If one of your site’s web pages appears as the third organic entry listed on the first page of Google for that query, we’d say you rank #3. If it was the #3 entry on the second page, we’d say you rank #13. Each Google SERP traditionally has 10 organic entries (there are situations where there may be fewer, but the norm is 10 entries), but the number of SERPs per query can vary somewhat significantly (i.e. one search query may result in 8 pages of entries, while another might result in 10 + pages of entries). You may be wondering why this matters? Let’s review.

The higher your site ranks in Google’s SERPs, the more traffic is available to your website: 95% of search traffic doesn’t proceed beyond the first page of Google’s SERPs. Even more astounding, perhaps, is the amount of traffic that the top 3 positions on Google’s Page 1 receive. If your website doesn’t appear in one of the first 3 entries on Google Page 1, you’re missing out on as much as 75% of the organic traffic associated with that search query. Higher rankings aren’t just a matter of pride or hubris; they correlate strongly with more traffic and increased click-through-rates.

For an illustrative example, take a look at the image below of the top 3 search results for the query “plumbing services in Idaho” (highlighted by orange boxes). If the query averaged a monthly volume of 1,000 searches, and 75% of all Google SERP traffic goes to the entries in the top 3 positions, that means roughly 750 visitors are going to click-through one of the top 3 entries, leaving 20% to disburse amongst the remaining 7 entries on Page 1. The final 5% of associated search traffic will make its way onto Page 2, 3, 4, etc. The value of being on Page 1, or being in the Top 3 of Page 1, is evident. That’s where the traffic comes from.

What Core Web Vitals Are (Made Easy)

This is a brief overview of the core web vitals as applied by Google. Being a developer with a deep understanding of these metrics is not necessary, but if you are a business owner, or if you manage a website, you’ll want to have at least a general understanding of how Google is evaluating these measurements. After all, they may soon have a profound effect on your organic search rankings.

Core web vitals, as used by Google, is an umbrella term inclusive of three website speed/UX-related metrics reflective of a user’s experience when loading a web page. They directly reflect measurements of web page load speed, responsiveness to input, and element shift during load. Specifically, Core Web Vitals refer to Largest Contentful Paint (LCP - load speed), Cumulative Layout Shift (CLS - element shift during load) and First Input Delay (FID - responsiveness to input). More complete information about each of these elements is listed below.

Largest Contentful Paint (LCP)
The time it takes for a page’s main content to load. Google has stated that this is a measurement of the render time of the largest visible image or text block. This means that if you have large images or video backgrounds that take a long time to load on your site, your LCP is going to be negatively affected.

First Input Delay (FID)
The time it takes for a page to become interactive. When a page loads the user expects to be able to interact with elements on the page such as a form or button as they appear. You’ve probably encountered situations where you were unable to scroll or interact with a page for a period of time as it continues to load on your screen. First input delay measures the delay in processing user inputs on your page while the page is loading.

Cumulative Layout Shift (CLS)
The amount of unexpected layout shift of visual page content while a page is loading. If you’ve ever seen buttons, menus, images or other elements move around on the page while it is loading this is now taken into account by Google as cumulative layout shift. Google flags this as negative user experience.

According to Google, “these signals measure how users perceive the experience of interacting with a web page and contribute to our ongoing work to ensure people get the most helpful and enjoyable experiences from the web.” As such, these metrics are being used to evaluate how good/bad the user experience is for site visitors on a web page.

Section Summary
Core web vitals include measurables universal to all websites and will serve as a ranking factor upon implementation of Google’s June 2021 Core Algorithm Update (pushed back from May).

Metrics measured include page load speed (LCP), content shift on page load (CLS), and time until the page becomes interactive on load (FID). These metrics are meant to reflect user experience with the web page.

So, what is Google really doing? They’re incentivizing the cessation of certain site behaviors that tend to frustrate users: slowly loading pages/sites, content that shifts or moves due to ad displays, etc., and content that prevents users from interacting with the page immediately upon load (pop-ups, anyone?).

How Will Core Web Vitals Impact Rankings?

Regarding core web vitals and Google’s impending June 2021 Core Algorithm Update, they have the potential to cause some noticeable ranking disruption. Web pages that meet all 3 criteria for core web vitals are eligible for a ranking boost. Sites that don’t, are not. This is an extremely rare case of Google saying “yes, we are going to measure these items, and if you meet such-and-such criteria you will receive a ranking boost”. As such, it’s a unique opportunity to try and move above competitors in the SERPs by addressing an item specifically identified as being included with a Google Core Update.

If your website is not optimized for these metrics, it may experience a “ranking drop” during the June update. This is not Google penalizing your site (there is no penalty). Rather, competitors who have addressed core web vitals in anticipation of the June update may receive the extra ranking juice needed to pull ahead of your non-optimized site.

Section Summary

As part of the June 2021 Algorithm Update, websites that meet all 3 of the standards established by Google for core web vitals will be eligible for a ranking “boost” - i.e. core web vitals will be another ranking signal, but you must meet the criteria for all three to achieve any benefit.

There is no penalty for failing to meet Google’s Core Web Vitals criteria. Rather, your site may appear to drop as sites that meet the criteria rise in rankings in Google’s SERPs..

How to Easily Check Your Site’s Core Web Vitals

Checking if your website meets Google’s Core Web Vitals metrics is an easy process when using the following highly recommended tool:


Click the link to this website and you’ll see the homepage dashboard (depicted in the screenshot below). Enter the URL/web address of your website’s homepage in the input bar and click the “Test your site” button (alternatively, copy and paste your website’s URL)..

GT Metrix will then run a test on your URL and generate a detailed site speed report. It should look similar to the report in the screenshot below. Under the section titled “Web Vitals”, in the red square, you’ll see your score for each core web vital metric.

If any of the numbers in your report are orange or red, it means they don’t currently meet Google's established core web vitals criteria. As such, they will need to be improved to protect your site’s organic SERP rankings.


Google’s Core Web Vitals Criteria

LCP (Largest Contentful Paint) <in blue square> - For a good user experience, aim for an LCP of 1.2 seconds or less.

TBT (this is the same as First Input Delay or FID) <in green square> - For a good user experience, aim for a TBT of 150 milliseconds or less.

CLS (Cumulative Layout Shift) <in orange square> - For a good user experience, aim for a CLS score of 0.1 or less.

You can also use the easy-to-follow guidance outlined above to examine your competitors’ core web vitals. The number of sites surrounding your organic search rankings that have already prepared for adoption of core web vitals as a ranking factor might surprise you. If they haven’t, that’s an outstanding opportunity for you.

Section Summary

  • Use GT Metrix to analyze your (or your competitor’s) website speed and core web vitals
  • LCP should be less than 1.2 seconds
  • FID should be less than 150 milliseconds
  • CLS should be less than 0.1 (this is not a time measurement, but a measurement developed by Lighthouse in 2021)


If your website is ill prepared for Google’s June 2021 Core Algorithm Update, specifically as it relates to core web vitals, your organic SERP entries are vulnerable to unfavorable ranking adjustments. Don’t waste this opportunity. Use the guidance above to check your site’s core web vitals and address any issues or deficiencies as quickly as possible to ensure all criteria are met. Mid-June is fast approaching, so there’s little time to wait.

Technical correction of the various items that might be impacting your website’s core web vitals is beyond the scope of this article. If you’re concerned about providing your users with a good web experience and want to position your site for improved rankings, contact your webmaster or development team to discuss Google’s June 2021 Core Algorithm Update as soon as reasonably possible. Work optimizing for Google’s core web vitals standards can range from simple to complex, and you may not be able to affect this work on your own. Your webmaster and/or dev team should be able to help..

If your business doesn’t have a dedicated webmaster or developer, contact SEO Idaho for a free Core Web Vitals Audit. We’ll assess your current core web vitals and discuss your options for corrective action. Stay ahead of the pack, boost your rankings, and improve site visitor UX by addressing your site’s core web vital deficiencies today.