Websites · Glossary
What are Core Web Vitals?
Core Web Vitals are three measures Google uses to describe how a page feels to real visitors: Largest Contentful Paint for loading speed, Interaction to Next Paint for responsiveness, and Cumulative Layout Shift for visual stability. Good scores are LCP within 2.5 seconds, INP within 200 milliseconds and CLS below 0.1, measured on real phones and computers.
The vitals turn page experience into numbers you can track. They come from real visitors when a site has enough traffic, which is why your score in a lab test can differ from the one in Search Console.
Nuwan Madhusanka · Co-founder
3 min read · Published
| Metric | Measures | Good | Poor |
|---|---|---|---|
| Largest Contentful Paint (LCP) | When the main content has loaded | 2.5 s or less | Over 4 s |
| Interaction to Next Paint (INP) | How quickly the page responds to taps and clicks | 200 ms or less | Over 500 ms |
| Cumulative Layout Shift (CLS) | How much the layout jumps while loading | 0.1 or less | Over 0.25 |
What each metric means
LCP marks when the largest image or text block in view finishes rendering, a proxy for the page looking ready. INP measures the delay between a tap or click and the next visual update across the visit. CLS adds up unexpected layout jumps, such as text moving when a late image or banner appears.
What usually hurts them
Large uncompressed images and slow servers hurt LCP. Heavy JavaScript, especially third party scripts, hurts INP. Images without set dimensions, late loading ads and embeds, and fonts that swap size hurt CLS. Most small business sites fail on images and third party embeds rather than anything exotic.
How much they matter for search
They are part of Google's page experience signals, which act as a tie breaker rather than a main ranking factor. Relevant, useful content still wins. Their bigger effect is on visitors: slow, jumpy pages lose people before they read anything, especially on phones.
Common mistakes
Chasing a perfect lab score instead of real visitor data, uploading photos straight from a camera, loading video players and maps at the top of every page, and adding several tracking scripts. Fix the largest image and the heaviest script first.
Where it shows up in OneCraft
Published sites are static pages on a CDN, with set image areas, maps that load only near the screen, and videos that load their player only after a click. Pages carry a small script for interactive parts and a one beacon visit counter, and Google Analytics loads only if you add an ID, all of which keep the vitals in a good range. Your own photo sizes still matter most.
Questions people ask
Where can I see my Core Web Vitals?
Google Search Console shows field data for pages with enough traffic in its Core Web Vitals report. PageSpeed Insights shows both field data, when available, and a lab test for any address. Lab tests are useful for spotting causes; field data shows what visitors actually experience.
Why is my mobile score worse than desktop?
Phones have slower processors and often slower connections, so the same page takes longer to load and respond. Lab tests also simulate a mid range phone on a throttled network. Mobile is where most small business visitors are, so it is the score to work on.
Do Core Web Vitals affect small local businesses?
They affect every site that appears in Google, but as a tie breaker. A local business with relevant content and good reviews will not be outranked just for a slightly slow page. A very slow page loses visitors who give up waiting, which costs more than any ranking effect.
What is the quickest way to improve LCP?
Make the largest element in the first screen load fast: resize and compress the hero image, serve it in a modern format, and avoid hiding it behind scripts or animations. Removing unnecessary scripts from the top of the page also helps the browser render sooner.
What replaced First Input Delay?
Interaction to Next Paint replaced First Input Delay as a Core Web Vital in March 2024. INP looks at responsiveness across all interactions during a visit, not just the first one, so it better reflects pages that become sluggish after loading.
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Written and checked by the OneCraft team. Last checked .