What do the three measurements check?
Each has a name, a job and a line Google draws for "good". Google's web.dev site ("Web Vitals") sets the thresholds, and a page passes when at least 75 percent of visits meet them.
| Measurement | What it checks | Good | Poor |
|---|---|---|---|
| Largest Contentful Paint (LCP) | How long until the biggest thing on screen, usually the main image or headline, has loaded | 2.5 seconds or less | Over 4 seconds |
| Interaction to Next Paint (INP) | How long the page takes to respond visibly after a tap, click or key press | 200 milliseconds or less | Over 500 milliseconds |
| Cumulative Layout Shift (CLS) | How much the content moves around unexpectedly while you read | 0.1 or less | Over 0.25 |
Interaction to Next Paint took First Input Delay's place in the set in March 2024. Between good and poor, Google labels results as needing improvement.
How much do they count in Google's rankings?
Some, and less than the page's content. Google Search Central's "Understanding Core Web Vitals and Google search results" says its ranking systems use Core Web Vitals, and also that good results do not guarantee a high ranking: Google still aims to show the most relevant page, even when its page experience is weaker. A fast page about the wrong thing will not outrank a slower page that answers the search.
The stronger reason to care is the visitor. A shopper on a phone who waits five seconds for a photo, or taps "Add to cart" just as an image pushes the button down, is a shopper who leaves.
What did a Bowral florist gain from a faster order page? (example figures)
A florist in Bowral takes orders online for delivery across the Southern Highlands, with an average order of $85. Its product pages opened with a 4 MB photo and a promotion banner that loaded last and shoved everything down. PageSpeed Insights, run on a product page, showed LCP at 5.8 seconds on mobile and CLS at 0.31, both poor.
The fix took a morning: the photo was resized and compressed to about 250 KB, and the banner was given its space in the layout before it loaded. LCP fell to 2.1 seconds and CLS to 0.04. Over the next month, about 3,000 mobile visits reached product pages, as before, and mobile orders rose from 42 to 60, a conversion rate of 2.0 percent instead of 1.4. The 18 extra orders were worth about $1,530 in sales that month, from work that cost nothing to keep.
Why does Search Console say there is not enough data?
Because the measurements come from real visitors, and a small site may not have enough of them. Core Web Vitals in Search Console are drawn from the Chrome User Experience Report, which only reports pages and sites with enough Chrome traffic. Many owner-sized websites see "Not enough data" for some or all pages. In that case, run the page through PageSpeed Insights, which also runs a lab test on a simulated phone, and fix what it flags on the pages that take orders or enquiries.
How does CoraVision connect page speed to sales?
CoraVision judges a speed fix by the orders that follow it. From Google Analytics 4 it reads purchases and revenue, along with visits by channel and key events, and refreshes them every night, so the weeks after a fix can be compared with the weeks before. You run the speed test with Cora looking at the result on your screen. The changes to the site are made by you or your web developer.
Questions
What happened to First Input Delay?
Google replaced it with Interaction to Next Paint in March 2024. First Input Delay measured only the first tap or click on a page; Interaction to Next Paint looks at the responses across the whole visit, which is closer to how a page feels to use.
Is the PageSpeed Insights score the same thing?
Not quite. The 0 to 100 performance score comes from a lab test run once on a simulated device. The Core Web Vitals assessment at the top of the same report comes from real Chrome users over the past 28 days, when Google has enough of them, and that is the one Search uses.