Core Web Vitals is rolling out from June 2021 until August 2021.
Also known as the Page Experience Update, this change to the Google ranking algorithm will give more weight to the user experience of a given web page.
What will Core Web Vitals measure?
The main three things you should focus on as a site owner are Cumulative Layout Shift (CLS), First Input Delay (FID), and Largest Contentful Paint (LCP). You can measure where any given web page rates for desktop and mobile using a free tool called Page Speed Insights.
Google representatives have said your page will get a “slight boost” if all three of these measurements are a passing grade. No word on how much that will effect rankings, but you should aim for any incremental rankings boost you can obtain.
Let’s talk about each of these measurements in more detail.
Largest Contentful Paint (LCP)
LCP measures how long it takes to load the largest page element in your browser window when you land on the page. A good time is less than 2.5 seconds to load the largest “above the fold” element on mobile and desktop. Page Speed Insights will list the Largest Contentful Paint element as a line item for desktop and mobile. Usually, the largest element on initial screen load is an image or headline text. If you can figure out how to load these quickly, you will have a good LCP score.
First Input Delay (FID)
FID measures how long it takes the page to start loading in the browser. Under 100 milliseconds is the target you should be aiming for. Usually, if you have professional hosting, and defer loading any render-blocking scripts and files, this will lower your FID to an acceptable speed level.
Cummulative Layout Shift (CLS)
CLS measures how much the layout of the page shifts from the time the page starts loading until it is fully loaded. When page elements realign from the point of first loading the page to fully loaded, that affects CLS. Page Speed Insights shows small screenshots of the page loading to give you clues as to what elements may be shifting. Getting CLS to an acceptable level requires some thoughtfulness about how you build your site, and you may need a web developer’s help to improve this. (Some advice: If you plan on redesigning your website soon, hire someone to build it correctly from the start, instead of optimizing after the fact.)
Video Recaps of Core Web Vitals
Back in spring of 2021, I made a video to recap the changes with page experience, and what things you should focus on in optimizing your website: https://www.youtube.com/watch?v=3sLyx3OOv5M.
I also recently sat down with Jonathan Denwood and Steven Sauder of the WP-Tonic podcast to discuss how these changes might affect rankings: https://www.youtube.com/watch?v=MPEokrOTYOQ.