Google will implement its latest search ranking factor, Core Web Vitals, in 2021.
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By Phil Frost

52 mins ago

The fact that page speed matters when it comes to SEO is nothing new. We’ve been hearing from Google for years that they use page speed as a ranking factor and we’ve been designing, revising and redesigning websites ever since. Now, starting next year, Google is rolling out a new ranking factor that takes a more granular approach to page speed: Core Web Vitals. What does this mean for you and your website? Here’s what you need to know.


Google describes Core Web Vitals as real-world page experience metrics, but the page experience in question is all about speed. While the traditional way to measure page speed was to determine loading time, Core Web Vitals breaks speed down into three separate metrics:

Largest contentful paint (LCP) is the amount of time it takes for a page’s main content—its largest image or text block—to load in the viewport. It is closest to what we defined as site speed in the past.

If you’ve ever been reading a news website or blog on your phone and attempted to tap a headline only to have an ad load under your finger instead, you know all about cumulative layout shift (CLS). This metric measures how much shifting or displacement occurs in the viewport while a page loads. It’s scored between 0 and 1, with 1 being the most shifting and worst user experience.

First input delay (FID) measures the amount of time until a page is interactive. When there is a delay between a page loading in the viewport and the ability for users to interact with the content (click, scroll or type in text fields), this has a negative impact on your Core Web Vitals ranking.

How to find

Although Google won’t begin using Core Web Vitals as ranking factors until the upcoming page experience update in 2021, you can start working on improving these metrics now. 

Google grades each of the metrics outlined above as Good, Needs Improvement or Fail. You can find your Core Web Vitals report in the Google Search Console, which breaks down your page performance by URL.  Once you’ve found the report, you can go to the overview page and toggle between the tabs for each of the three grades to see the URLs on your site that are performing well and the ones that need to be worked on—these can be broken down by desktop or mobile. 

Tips for improving 

Many of the same fixes that are used to improve overall page speed will also help with your Core Web Vitals. Google suggests:

  • Reducing page size, ideally to less than 500KB.
  • Limiting the number of page resources to 50 for optimal mobile performance.
  • Using AMP for improved page loading. offers tips specific to each of the Core Web Vitals metrics—these are excellent resources that everyone who works in SEO or web development should bookmark:

Use the PageSpeed Insights testing tool to test any changes you make, then click Start Tracking on the issue details page in your Core Web Vitals report to validate the fixes.

The bottom line

It’s easy to get frustrated when you find out you’ve got to start accounting for yet another new ranking factor, but Core Web Vitals reflect what we should be doing anyway—creating websites that are functional and usable

Even if Google wasn’t using these metrics for ranking, having a site with poor user experience naturally drives people away. With so many options available, users are more likely to simply hit the back button and find another website than stay on a site that’s a hassle to use. Unlike so many other algorithm changes that seem arbitrary, Core Web Vitals is one that really does help us build better websites.

Phil Frost

Phil Frost is founder and COO of digital marketing agency Main Street ROI.