How important are Core Web Vitals
for SEO?

Core Web Vitals are an important part of SEO, but they are frequently misunderstood.

A fast, responsive and visually stable website can provide a better experience and contribute to stronger search performance. However, passing every Core Web Vitals assessment will not automatically move a website to the top of Google.

Google still prioritises relevant, useful and trustworthy content. Core Web Vitals become particularly valuable when several pages provide similarly strong answers and Google needs to decide which one offers the better overall experience.

Businesses should therefore take Core Web Vitals seriously without treating them as the only measure of SEO success. Our SEO service balances technical performance with content and authority work.

What are Core Web Vitals?

Core Web Vitals are three measurements Google uses to evaluate the real-world experience of visiting a webpage.

They measure:

• How quickly the main content appears
• How promptly the page responds to interaction
• How visually stable the page remains while loading

Google currently uses three Core Web Vitals:

Google recommends assessing these results at the 75th percentile of page visits. This means a page should provide a good experience for at least 75 percent of users, rather than performing well only on ideal devices and internet connections. Google Web Vitals guidance

Largest Contentful Paint

Largest Contentful Paint, or LCP, measures how long it takes for the largest visible content element to appear.

This is often:

• A hero image
• A large heading
• A product photograph
• A banner
• A prominent block of text
• A video preview image

A good LCP is 2.5 seconds or less.

LCP matters because it represents the moment when a visitor feels that the page has meaningfully loaded. A browser may display the header or background quickly, but the page still feels slow if the main content remains missing.

Common causes of poor LCP include:

• Slow hosting
• Large hero images
• Images in inefficient formats
• Too many redirects
• Delayed fonts
• Render-blocking scripts
• Client-side rendering
• A slow server response
• Important content loaded by third-party software

Improving LCP often requires more than compressing images. The development team may need to review how the page is generated, hosted and delivered.

Interaction to Next Paint

Interaction to Next Paint, or INP, measures how quickly a page provides visual feedback after a user interacts with it.

The interaction might involve:

• Opening a navigation menu
• Selecting a filter
• Clicking a button
• Opening a dialog
• Adding an item to a basket
• Switching tabs
• Completing a form field

A good INP is 200 milliseconds or less.

A page can appear to load quickly but still feel frustrating if it pauses after every click. This often happens when the browser is processing too much JavaScript or performing a complicated task on its main thread.

Common causes of poor INP include:

• Excessive JavaScript
• Large third-party scripts
• Complicated event handlers
• Inefficient page updates
• Heavy analytics and advertising tools
• Long-running browser tasks
• Poorly implemented interactive components

INP is measured using genuine user interactions, so it cannot be fully reproduced by a simple automated page-load test. Laboratory tools often use Total Blocking Time as an approximate diagnostic measurement, but real-user data is needed to understand actual INP performance. Google guidance on measuring Web Vitals

Cumulative Layout Shift

Cumulative Layout Shift, or CLS, measures how much visible content moves unexpectedly.

A good CLS score is 0.1 or less.

Common examples include:

• A button moving just before someone selects it
• Text shifting when a font loads
• An advert appearing above the article
• A cookie banner moving the page content
• An image expanding because its dimensions were not reserved
• A form changing position when an error appears

Unexpected movement is more than a visual annoyance. It can cause visitors to select the wrong link, lose their place or mistrust the website.

CLS can often be improved by:

• Reserving space for images and videos
• Setting image dimensions
• Loading fonts appropriately
• Avoiding content inserted above existing content
• Giving adverts and embeds fixed containers
• Designing validation messages so they do not move the form unexpectedly

Are Core Web Vitals a Google ranking factor?

Yes, Core Web Vitals are used by Google’s ranking systems.

However, Google does not describe them as a single dominant ranking factor. They form part of a wider assessment of page experience.

Google explicitly states that achieving strong Core Web Vitals does not guarantee a top position. Its systems will normally continue to prioritise the most relevant content, even when that content provides a weaker page experience. Google page-experience guidance

This means a fast but unhelpful page is unlikely to outrank a slower page that answers the search properly.

Core Web Vitals are most likely to make a difference when:

• Several pages offer similarly relevant information
• Competitors have comparable authority
• Users frequently visit from mobile devices
• The market is commercially competitive
• Performance problems make a page difficult to use
• Poor experience causes visitors to abandon the site

The correct approach is to combine useful content with a good experience, not to choose one over the other.

Why they matter beyond rankings

The commercial importance of Core Web Vitals may be greater than their direct ranking impact.

SEO does not end when a person selects a search result. The website still needs to persuade that visitor to remain, understand the offer and take action.

Poor performance can interfere with:

• Enquiry forms
• Product purchases
• Appointment bookings
• Demonstration requests
• Telephone calls
• Content consumption
• Customer confidence

A website may rank well and still produce disappointing results if visitors find it slow or difficult to use.

This is why Core Web Vitals should be considered part of conversion optimisation as well as technical SEO. See our convert more use case for the wider picture.

Mobile performance matters most

A website that performs well on an office computer may provide a very different experience on a mobile phone.

Mobile visitors may have:

• A slower connection
• An older device
• Less processing power
• A smaller screen
• Limited data
• More distractions
• Less patience with delays

Google uses the mobile version of a website’s content for indexing and ranking. It strongly recommends providing a mobile-friendly experience and ensuring that Google can access the same important content and metadata on mobile. Google mobile-first indexing guidance

When evaluating Core Web Vitals, pay particular attention to mobile results and real users rather than relying only on a fast desktop test.

Field data and laboratory data are different

Core Web Vitals can be measured using two types of data.

Field data

Field data comes from real visits made by eligible Chrome users. It reflects actual devices, networks, locations and behaviour.

Google Search Console’s Core Web Vitals report uses this real-world data and groups pages with similar characteristics. Google Search Console Core Web Vitals report

Field data is what matters when determining whether pages pass Google’s Core Web Vitals assessment.

Laboratory data

Laboratory data is produced by running a controlled test using tools such as Lighthouse or PageSpeed Insights.

It is useful for:

• Reproducing performance issues
• Identifying likely causes
• Comparing changes
• Testing before release
• Finding improvement opportunities

Laboratory data is diagnostic. Field data shows what genuine visitors actually experience.

The two may not agree because real visitors use different devices, connections and page paths. Cookie notices, personalised content and interactions can also produce problems that do not appear in a simple automated test.

Why Search Console may not show every page

The Core Web Vitals report does not necessarily include every URL.

Google needs enough real-user data before it can report on a page or group of similar pages. A new website or a page with limited traffic may not have sufficient data.

An empty report does not mean the website is fast, slow or exempt from Core Web Vitals. It may simply mean that there is not enough field data.

In this situation, use PageSpeed Insights and Lighthouse for testing while collecting your own real-user monitoring where practical.

What usually causes poor Core Web Vitals?

Common causes include:

• Oversized images
• Slow hosting
• Heavy themes or page builders
• Excessive JavaScript
• Too many tracking scripts
• Advertising technology
• Live-chat tools
• Unoptimised fonts
• Cookie-management software
• Third-party video players
• Client-side rendering
• Poor caching
• Layouts without reserved space
• Complex animation
• Plugins loading code on every page

The problem is often cumulative. No single script appears especially damaging, but the combination of analytics, chat, advertising, personalisation and embedded media makes the page slow and unresponsive.

Our article on custom websites vs WordPress covers how architecture choices affect performance and maintenance.

Which pages should be fixed first?

Do not begin by attempting to produce a perfect score across every URL.

Prioritise pages that:

• Receive substantial organic traffic
• Rank close to the top positions
• Generate enquiries or sales
• Serve as important landing pages
• Have poor Core Web Vitals
• Represent templates used across many pages

Fixing one service-page template could improve dozens of URLs at once.

A sensible order is:

1. Pages with poor results and meaningful organic traffic
2. Important conversion pages
3. Templates affecting large groups of URLs
4. Pages marked as needing improvement
5. Low-value or rarely visited pages

This ensures that development time is connected to commercial impact.

Should you aim for a perfect PageSpeed score?

Not necessarily.

A perfect laboratory score can become expensive to maintain and may require removing features that provide genuine customer value.

Google advises that pursuing a perfect score solely for SEO may not be the best use of time. Core Web Vitals should support a strong overall page experience rather than becoming an isolated technical target. Google page-experience guidance

The priority should be:

• Passing the Core Web Vitals thresholds consistently
• Removing serious user frustrations
• Improving important page templates
• Preventing performance from deteriorating
• Balancing speed with necessary functionality

Moving from poor to good is generally more valuable than moving from good to technically perfect.

How to improve Core Web Vitals

A practical improvement programme should include:

Improve the main content load

• Compress and resize images
• Use modern image formats
• Prioritise the main image
• Improve server response time
• Use caching and a content delivery network
• Remove unnecessary redirects
• Avoid loading main content through delayed scripts

Reduce browser work

• Remove unnecessary JavaScript
• Split large bundles
• Delay non-essential scripts
• Review analytics and marketing tags
• Simplify complex components
• Avoid loading features on pages where they are not used

Prevent unexpected movement

• Set image and video dimensions
• Reserve space for embeds and adverts
• Manage font loading
• Avoid inserting content above existing content
• Design stable cookie banners and form messages

Monitor after every release

Performance can deteriorate when teams add:

• A new tracking platform
• A larger hero image
• An embedded video
• A live-chat service
• A new font
• A marketing popup
• An updated theme or plugin

Core Web Vitals should be monitored continuously rather than checked only during a redesign.

How important are Core Web Vitals overall?

Core Web Vitals are important, but they are one part of a much larger SEO picture.

A useful way to think about the priorities is:

1. Make sure Google can crawl and index the page.
2. Publish content that answers the search properly.
3. Demonstrate genuine experience and authority.
4. Earn relevant references and links.
5. Provide a strong mobile page experience.
6. Achieve good Core Web Vitals.
7. Make it easy for visitors to take the next step.

A technically perfect page with weak content will usually struggle. A valuable page with poor performance may rank, but it could lose visitors and conversions unnecessarily.

The strongest websites do both.

Core Web Vitals protect the value of your SEO

Core Web Vitals should not be treated as a shortcut to higher rankings.

Their real value is that they help ensure the traffic earned through SEO is not wasted on a slow, unresponsive or unstable website.

Google uses Core Web Vitals within its ranking systems, but relevance remains more important. Businesses should focus first on providing the best answer, then make sure that answer is delivered through a fast and dependable experience.

Good content earns the visit. Good Core Web Vitals make it more likely that the visitor stays, trusts the business and takes action.