By the Seovoro Team · Last updated October 6, 2026
Key takeaways
- Core Web Vitals measure loading (LCP), responsiveness (INP) and visual stability (CLS).
- Google considers LCP of 2.5 seconds or less, INP of 200 milliseconds or less and CLS of 0.1 or less to be good.
- Lab tests are useful for fixing problems. Field data from real users is what shows the real experience.
- On our own site, removing third-party fonts and icons from the first paint cut lab LCP from 3.6 s to 1.0 s.
Core Web Vitals are three measurements of how a page feels to use: how fast the main content appears, how quickly it responds and whether it jumps around. This guide explains each one in plain language, shows what a good result looks like and what we changed to improve ours.
In this guide
- The three metrics
- What is a good score?
- Lab data vs field data
- How to improve LCP
- How to improve INP
- How to improve CLS
- Our own numbers
- Frequently asked questions
- Sources
The three metrics
- Largest Contentful Paint (LCP) measures how long the largest visible element, often a heading or image, takes to appear.
- Interaction to Next Paint (INP) measures how quickly the page responds when people click, tap or type.
- Cumulative Layout Shift (CLS) measures how much the page layout moves unexpectedly while it loads.
What is a good score?
| Metric | Good | Needs improvement | Poor |
|---|---|---|---|
| LCP | 2.5 s or less | 2.5 to 4 s | Over 4 s |
| INP | 200 ms or less | 200 to 500 ms | Over 500 ms |
| CLS | 0.1 or less | 0.1 to 0.25 | Over 0.25 |
These thresholds come from Google and are described on web.dev: LCP, INP and CLS.
Lab data vs field data
Lab data comes from a simulated test, such as Lighthouse in PageSpeed Insights. It is repeatable and good for finding problems. Field data comes from real visitors over time and shows the experience people actually have. INP in particular needs field data. A new site may have no field data yet, which is normal. Our own report says so too.
How to improve LCP
- Make sure the server responds quickly.
- Avoid loading fonts, icons and widgets from other websites before the first paint.
- Compress images and size them correctly.
- Do not lazy-load the main image at the top of the page.
- Keep render-blocking CSS and scripts small.
How to improve INP
- Break up long JavaScript tasks.
- Remove scripts you do not need.
- Delay non-essential scripts until after the page has loaded.
- Keep the page structure simple.
How to improve CLS
- Set width and height on images and videos.
- Reserve space for ads, embeds and icons.
- Use
font-display: swapand load fonts early. - Avoid inserting new content above existing content.
Our own numbers
When we tested seovoro.com on mobile, our lab LCP and First Contentful Paint were both 3.6 seconds, even though the server answered in 57 ms and CLS and Total Blocking Time were already zero. The cause was fonts and icons loaded from other websites. After hosting the fonts ourselves and loading the icons after the page, mobile Performance went from 81 to 100 and LCP fell to 1.0 second. Read the full story in our case study. These are lab results, and we do not yet have real-user data.
To check your own site, use our free Site Speed Tester.
Frequently asked questions
Are Core Web Vitals a ranking factor?
They are part of Google's page experience signals, but content relevance and quality matter far more. Treat speed as a way to help visitors and remove weaknesses.
What replaced First Input Delay?
Interaction to Next Paint (INP) replaced First Input Delay as a Core Web Vital.
Why do my lab and field scores differ?
Lab tests simulate one device and network. Field data reflects many real devices, locations and connections.
Is a score of 100 necessary?
No. Pass the Core Web Vitals thresholds and focus on a good experience.
What is the quickest win?
Often, removing or delaying third-party resources and compressing images.
Can Seovoro help?
Yes. Speed and Core Web Vitals are part of our technical SEO audit.
Sources
- web.dev: Web Vitals
- web.dev: Largest Contentful Paint
- web.dev: Interaction to Next Paint
- web.dev: Cumulative Layout Shift
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Written by Seovoro SEO Team
SEO, AEO & AI Search specialists at Seovoro. View author profile