Core Web Vitals: which thresholds to aim for, and do they matter for SEO?
The short answer
Google considers a page fast when its main content appears within 2.5 seconds (LCP), it responds to clicks within 200 milliseconds (INP) and its layout barely shifts (CLS under 0.1), measured across 75% of visits. These metrics are used in ranking, but Google reminds site owners that relevant content comes first.
What do the three Core Web Vitals measure?
Core Web Vitals are three metrics defined by Google to measure the experience of a page. These are the "good" thresholds it publishes in its Search Central documentation:
| Metric | What it measures | Threshold to aim for |
|---|---|---|
| LCP (Largest Contentful Paint) | How long the largest visible element takes to appear, often the main image or heading | Under 2.5 seconds |
| INP (Interaction to Next Paint) | How quickly the page responds to a click, tap or key press | Under 200 milliseconds |
| CLS (Cumulative Layout Shift) | How much the layout shifts while loading | Under 0.1 |
INP is the newest: it became an official metric in 2024, replacing FID, which only measured the first interaction.
Why the 75th percentile?
Because a page doesn't have one speed, it has thousands: one per visit, depending on the phone, the network and the country. On web.dev, Google recommends looking at the 75th percentile of visits, mobile and desktop separately.
In practice, a page passes a threshold if at least 75% of visits meet it. The slowest 25% don't count, but most visits have to be in the green.
Do Core Web Vitals push a website up in Google?
Yes, to a degree, and Google is fairly precise about that degree. On its page about page experience, it states that:
- Core Web Vitals are used by its ranking systems;
- there is no single page experience signal;
- good results don't guarantee a top ranking;
- Google always tries to show the most relevant content, even if the experience is weaker.
In other words, a slow page that answers the question perfectly can beat a fast, empty one. With equal content, though, speed can make the difference. And it matters to your visitors anyway: a page that takes a while to appear on a phone loses some of them before they have even seen it.
How do I measure my website's Core Web Vitals?
Two free Google tools are enough:
- PageSpeed Insights, page by page. It shows two different things: field data (real visits, if the website has enough) and a lab test with a score out of 100.
- Search Console, "Core Web Vitals" report, to see at a glance which pages have issues, on mobile and on desktop.
On a new or low-traffic website, field data is often missing. The lab test is then the best indicator available.
What usually drags results down?
The same causes come up again and again:
- heavy images, especially the main image at the top of the page, which delays LCP;
- fonts loaded from an external service, which make text "jump" as it appears;
- third-party scripts (chat, advertising, tracking tools) that keep the browser busy and slow down clicks;
- elements inserted without reserved space, such as a banner or an image without dimensions, which shift the page.
None of these fixes is spectacular. Added together, they change the result.
What does it look like on a real website?
The Sea Kayak Adventures website scored under 60% on every Google PageSpeed metric before its rebuild. Afterwards, it was above 90%.
96 /100 for accessibility
/100 for accessibility
- performance
- 91
- SEO
- 100
Source: Google PageSpeed Insights, kayakmauritius.com, desktop version
That lab score alone doesn't explain the project's results (local top 3 in 2 weeks, 75% more enquiries), which also come from the Google Business Profile. But a fast website was the starting condition. It is also what I check first in an SEO audit, right after indexing.
Frequently asked questions
Is the PageSpeed score the same thing as Core Web Vitals?
No. The score out of 100 in PageSpeed Insights comes from a lab test on a simulated device. The Core Web Vitals that matter to Google are measured on real visits, when your website has enough of them. A good lab score helps, but field data is what counts.
Should I aim for 100/100?
No. Google itself writes that chasing a perfect score just for SEO may not be the best use of your time. Getting all three thresholds into the green is enough; beyond that, time is better spent on content.
Can a WordPress website have good Core Web Vitals?
Yes, but the theme, plugins and scripts added over time weigh heavily. It is one of the reasons I code most websites from scratch, as I explain in the custom website or WordPress comparison.
Are the thresholds the same on mobile and desktop?
Yes, but they are measured separately: Google recommends looking at the 75th percentile of visits, mobile and desktop apart. A website that is fast on desktop can be slow on a phone.
Sources
- Understanding Core Web Vitals and Google search results · Google Search Central
- Understanding page experience in Google Search results · Google Search Central
- Web Vitals · web.dev (Google)