Google introduced Core Web Vitals as a set of UX performance metrics designed to measure real-world page experience. Since then, we’ve learned a lot more about these metrics and what affects them.
Similarly to page load speed and mobile friendliness, the goal of Core Web Vitals is to make sure websites are providing a better experience for users. More specifically, these metrics tell you if your pages are:
- Fast enough to keep a user’s attention
- Responsive enough to feel usable
- Stable enough to not annoy people
Not only do users prefer sites with a great page experience, but these factors also contribute to your ranking results. Here’s how the Google Page Experience breaks down.
What are Core Web Vitals?
Core Web Vitals are a set of page experience metrics related to page speed, responsiveness and visual stability. They take the following into account:
- How fast does a page load?
- Does content on a page shift unexpectedly?
- Does the main content on the page load first?
- Are there intrusive popups or elements that disrupt the experience?
- Does the page respond quickly when a user interacts, or does it feel slow or unresponsive due to heavy scripts?
The actual metrics are known as:
- Largest Contentful Paint (LCP): Page speed/loading
- Interaction to Next Paint (INP): Responsiveness
- Cumulative Layout Shift (CLS): Visual stability
Core Web Vitals are part of an existing group of page experience metrics that include mobile-friendliness, security (Https instead of Http), intrusive popups, and safe browsing.
If you’ve read older articles (including the earlier version of this one), you’ll remember First Input Delay (FID). FID was the original “interactivity” Core Web Vitals metric. But Google replaced it with INP in March 2024, because INP provides a more comprehensive measure of page responsiveness.
What affects Core Web Vitals?
Let’s review each Core Web Vitals metric, what affects each metric and how to optimize for Core Web Vitals.
- Largest Contentful Paint (LCP): “Did the main content show up quickly?”
This measures the speed at which a page’s main content is loaded and appears on the screen. Basically, how fast the page loads. This is affected by render time, large images, background video, and text in the viewport (the visible part of the webpage to the visitor). (Target: within 2.5 seconds). - Interaction to Next Paint (INP): “Did the page respond quickly when I tried to use it?”
This measures interactivity/responsiveness, or how quickly a page reacts to user input. This is affected by JavaScript, third-party code and scripts, and long tasks on the main thread. (Target: under 200 milliseconds). - Cumulative Layout Shift (CLS): “Did anything jump around and make me misclick?”
This measures how often users experience unexpected layout shifts (a.k.a the “annoyance” metric). Does the content on the page (buttons, CTAs, etc…) shift unexpectedly? This is usually affected by image size, animations, or multiple fonts. (Target: Less than 0.1).
Where can I find my Core Web Vital scores?
Core Web Vitals are real-user performance metrics that Google summarizes over time, typically at the 75th percentile. Here are two easy ways to review them:
1. Google Search Console (best for a site-wide view)
This is the simplest place to start because it shows how your pages perform on mobile vs. desktop, and groups issues so you can prioritize fixes.
What it’s best for:
- Spotting patterns (“lots of URLs failing for the same reason”)
- Prioritizing which templates or page types to fix first
- Seeing improvements after you’ve made changes
2. PageSpeed Insights (best for a single page + diagnosis)
PageSpeed Insights gives you two useful views in one place:
- Field data (real user experience data) when available
- Lab data (simulated load of a page) to help you debug what’s causing the problem (Google for Developers)
What it’s best for:
- Checking a specific important page (homepage, service page, top blog post)
- Diagnosing problems quickly
How do I optimize my website for Core Web Vitals?
I reached out to our lead web developer, Jessica Larsen, to get some insights on how to best optimize your website for Core Web Vitals and overall page experience. Here are the most common elements that cause slow page speed and poor PageSpeed Insight scores.
1. Images formats and size
Images are usually the biggest culprit for low scores. This includes hero images (those large images at the top of the page), in-line images, background images, etc… To fix this, you want to compress images, use correct dimensions and sizes, implement lazy loading, and set height and width attributes to image tags.
2. Videos
Instead of embedding large video files directly onto your website, use a 3rd party video hosting service like Vimeo, Wistia, or YouTube to serve videos to your visitors. This will reduce the bandwidth on your server and will deliver the appropriate video quality to the visitor’s environment. Lazy loading videos or deferring rendering the video until clicked will take some of the video loading away from the initial page load.
3. Tracking scripts
Avoid using third-party tracking scripts that are not relevant to your business or your marketing. Review the scripts included on your site. Go through Google Tag Manager and review all of the tags then ask yourself these questions:
- Are they needed on every page? If not, only use them on the appropriate pages.
- What’s the cost-benefit of these tags vs page speed? Remove any unnecessary tracking scripts.
- Do you need them at all? If not, save some money and get rid of them.
4. Fonts
We recommend not using any more than 8 total custom font variants on your website. This includes font families, font weights, and italic versions of the font.
Preloading the font assets that are required for this page will instruct the browser to load it immediately. Storing your fonts locally will also reduce the number of HTTP requests and DNS lookups.
5. Ads, Pop-ups, promo banners, etc…
Any change of layout that happens without prior user input will cause an unexpected layout shift. This will produce a bad CLS score and most importantly be super annoying to the visitor.
The fix would be to pre-determine the height and width of the space allocated for the ad or banner, so the page layout doesn’t shift when the ad is loaded. Avoid placing ads above other content so that when the webpage is fully loaded it doesn’t shift all the content below it.
6. CSS and Javascript
How quickly a page loads can be held up on loading large CSS and Javascript. Optimize the CSS and Javascript by minifying and combining. Try and eliminate CSS and Javascript calls for pages that do not need them or only defer them to when needed.
When making these updates, start with the pages that matter most: your homepage, service pages, and top landing pages. That’s where performance improvements actually change outcomes.
Note: We highly recommend that you talk to your web developers when optimizing your website. There’s a lot of technical knowledge that goes into each piece of the page experience update. If you want a deep dive into all things page experience and Core Web Vitals, watch this conversation we had with Mike King, SEO pro, from iPullRank.
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Mike King, iPullRank“There’s a lot to unpack about Core Web Vitals and why they’re important, but the gist of it is this: they simplify page performance metrics, and that makes our lives as SEOs, marketers, business owners, and developers a bit easier.” |
Can Core Web Vitals affect my rankings?
Yes, Core Web Vitals can affect rankings, but they’re not the kind of ranking factor that’s going to rescue a page that isn’t relevant, helpful, or trusted.
Google has over 200 ranking factors. Page experience is only one part of the equation.
Google’s own guidance is pretty consistent on this: their systems aim to reward content that provides a good page experience, but you shouldn’t focus on one or two UX metrics in isolation. The bigger goal is an overall great experience.
“A good page experience doesn’t override having great, relevant content. However, in cases where there are multiple pages that have similar content, page experience becomes much more important for visibility in Search.” – Google
Is page speed a ranking factor?
“I ran a PageSpeed report and my site got a bad score. My site is broken!”
Is Nike’s website broken?
No, it’s not broken. But it can be optimized to provide a better (and faster) user experience.
How fast your page loads is one metric in the overall page experience. Page speed alone is not a heavily weighted ranking factor. (Source: Google)
Why is page speed important?
Page speed is important because it alleviates the frustration involved in waiting for sites to load. It creates a better user experience which affects user engagement (how people interact with your website) and conversions (sales and leads).
What’s the ideal page speed score?
Don’t focus too much on the actual page speed scores.
Yes, there are things you can do to optimize your site to improve these scores, but Google themselves have said that there’s not a typical score that you should shoot for.
I highly recommend watching this video from Martin Splitt and John Muller from Google as they answer page speed questions.
“Just make sites fast for users.” [1:17] Martin Splitt, Webmasters Trend Analyst at Google. “You will never have a score that you optimize for and be done with it.”
The TL/DR: Core Web Vitals are just one piece of the puzzle
Core Web Vitals are Google’s three UX metrics for loading (LCP), responsiveness (INP), and visual stability (CLS).
They matter because they’re a proxy for friction, and friction hurts engagement and conversions. But, Core Web Vitals are only one piece of the puzzle when it comes to ranking, and content relevance, usefulness, and authority still come first.
Removing one popup from your website or reducing a few image sizes won’t affect page experience or rankings.
Optimize your site, continue to create great content, save yourself money by removing unneeded marketing tools and let’s all do our part to make the internet a better place.
