Technical SEO
June 17, 2021
6 minute read

June Algorithm Update, Core Web Vitals 2021

What on earth are core web vitals? What impact did they have on sites in Google's June/July 2021 Core Algorithm Update?
Jodie C Ball

June (and July) 2021 Core Algorithm Update: Core Web Vitals

Oh Algorithm Updates... we all have a love-hate relationship with core algorithm updates. To be honest, it's more like Stockholm Syndrome. 


Google announced a two part algorithm update:
Part 1 in June of 2021 that already rolled out on June 2nd, 2021. Apparently they weren't quite ready so they're releasing Part 2 in July.

Both algorithm updates are taking aim at Core Web Vitals, which is no surprise. Anyone with their ear to the ground in the SEO community has been pushing for enhanced page speeds for at least a year or two now. Users like fast pages, therefore, so does Google.

It seems, however, that every core algorithm update in the past 2 years has at least lightly touched page speeds -- now it's the focus, so it's going to be a wild ride for anyone who hasn't updated their site in a few years.  

⚠️ 🚨 So if your site's a little old, you have about 2 weeks to get it together and resubmit your sitemap for indexing to get credit for all of your changes in the July roll out. 🚨 ⚠️

What on earth are core web vitals?

Google's definition of Core Web Vitals Is (as always) vague and developer-jargon-heavy.

Essentially, Core Web Vitals is a set of data from real life user metrics. Google groups them into the following three categories: Largest "Contentful" Paint (LCP), First Input Delay (FID), Cumulative Layout Shift (CLS). As always, Google attempts to appease users first, so these metrics only are measured from the indexed URLs on your site.

Here's how Google defines those:

  • LCP (largest contentful paint): The amount of time to render the largest content element visible in the viewport, from when the user requests the URL. The largest element is typically an image or video, or perhaps a large block-level text element. This is important because it tells the reader that the URL is actually loading.
  • Agg LCP (aggregated LCP) shown in the report is the time it takes for 75% of the visits to a URL in the group to reach the LCP state.
  • FID (first input delay): The time from when a user first interacts with your page (when they clicked a link, tapped on a button, and so on) to the time when the browser responds to that interaction. This measurement is taken from whatever interactive element that the user first clicks. This is important on pages where the user needs to do something, because this is when the page has become interactive.
  • Agg FID (aggregated FID) shown in the report means that 75% of visits to a URL in this group had this value or better.
  • CLS (Cumulative Layout Shift): CLS measures the sum total of all individual layout shift scores for every unexpected layout shift that occurs during the entire lifespan of the page. The score is zero to any positive number, where zero means no shifting and the larger the number, the more layout shift on the page. This is important because having pages elements shift while a user is trying to interact with it is a bad user experience. If you can't seem to find the reason for a high value, try interacting with the page to see how that affects the score.
  • Agg CLS (aggregated CLS) shown in the report is the lowest common CLS for 75% of visits to a URL in the group.

Core web vitals in layman's terms

Here's how I define Core Web Vitals for humans instead of whatever robots Google thinks its talking to:

  • LCP (largest "contentful" paint): how fast the first and biggest element on your page takes to load. Usually your header image or video. Users don't want to sit around and see a blank page because it feels like your site isn't working. Make sure it loads fast. The score is from bad (0) to good (100), the metrics are in seconds or milliseconds.
  • FID (first input delay): this is your site's reaction time to clicks. When a users clicks something, your site should start doing whatever it's supposed to do pretty quick, otherwise users (again) think your site is broken or will click a button 1000 times in frustration to get things to load. Your site needs to react quickly to clicks. The score is in seconds or milliseconds.
  • CLS (cumulative layout shift): A score that measures how responsive your pages & elements are to the screen size or resizing. Ideally, your page detects the aspect ratio before it loads things, or at least reacts quickly to the screen size so someone doesn't accidentally click something they didn't intend to click. This metric is how many times the layout shifts.

Here's Google's recommendations on what those recommendations should be:

source: , "Status Definitions"

How do you know if your core web vitals might be an issue?

If you want to get a super detailed audit & report for your site (or even your competitors' sites), just visit this link, or visit and select "Measure" in the top menu. Once your audit runs, you can click the "view report" link at the top left of the page. This report will take you to a second page that details any major issues and elements that are holding back your core web vitals performance.

However, you can skim through some things on Google Analytics & Google Search Console to get somewhat of an indicator that you might have an issue, even if you're doing "okay" according to the audit.

  • On Google Analytics, check out your bounce rate for BOTH mobile & desktop (disregarding any ppc or ad sources of traffic because this could be indicative of a few other things for those channels, like misleading ad copy). If this number is higher than 65-70%, you probably have some load time issues.
  • On Google Analytics, if a higher portion of your traffic comes from mobile devices over desktop, but you still get more conversions & revenue on the desktop version of your site, you probably have core web vital issues.
  • On Google Analytics, if very few users are taking completing any events (scrolling, clicking, page depth, etc), you might have core web vital issues.
  • On Google Search Console, go to "Experience" > "Core Web Vitals" and view both the mobile and desktop reports. This will list each core web vital metric where your pages are failing. Anything listed as "poor" or "needs improvement" needs fixed.

Fixed the issues?

Great! Resubmit your sitemap in Google Search Console after every major fix you make. Time is so short to fix these things that you want those changes indexed ASAP -- something is always better than nothing because it's better to not lose your rankings or keywords in the first place rather than trying to earn them back.

Need Some Help?

Call me, text me, email me, or use my contact page!  I'm happy to help guide you through this process

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