TL;DR
- Largest Contentful Paint should be 2.5 seconds or less, Interaction to Next Paint 200 milliseconds or less, and Cumulative Layout Shift 0.1 or less.
- Interaction to Next Paint replaced First Input Delay as a Core Web Vital in March 2024.
- Google assesses each metric at the 75th percentile of real visits, separately for mobile and desktop.
- Big images, heavy scripts and images or ads without set dimensions cause most problems on small business sites.
Google’s Core Web Vitals boil page experience down to three numbers. Each has a “good” threshold, a “poor” threshold and a range in between that “needs improvement.”
The three metrics
| Metric | What it measures | Good | Poor |
|---|---|---|---|
| Largest Contentful Paint (LCP) | How long until the main content, often a hero image or headline, appears | 2.5 s or less | More than 4 s |
| Interaction to Next Paint (INP) | How quickly the page responds to taps, clicks and key presses | 200 ms or less | More than 500 ms |
| Cumulative Layout Shift (CLS) | How much the layout jumps around unexpectedly | 0.1 or less | More than 0.25 |
Interaction to Next Paint became a Core Web Vital on March 12, 2024, replacing First Input Delay. INP looks at responsiveness across the whole visit rather than only the first interaction.
Google evaluates each metric at the 75th percentile of page visits, so at least three out of four visits need to be “good” for a page to pass.
Where to find your numbers
- Search Console’s Core Web Vitals report groups similar URLs and uses real-user data.
- PageSpeed Insights shows field data for a URL or the whole site when available, plus a lab test with specific suggestions.
Common fixes, in order of payoff
- Shrink and size images. Oversized hero images are the most common cause of slow LCP; see image optimization.
- Don’t lazy-load the main image. Lazy loading below-the-fold images is good, but the image that forms your LCP should load right away.
- Set width and height on images, videos and embeds so the browser reserves space and the layout doesn’t shift.
- Cut third-party scripts. Chat widgets, trackers and sliders often hurt INP; remove the ones you don’t need.
- Use caching and a decent host. A slow server delays everything that follows.
Quick fix: Test on a mid-range phone over a cellular connection, not your office desktop. Most small business visitors arrive on phones, and that’s where problems show up; see mobile-first indexing.
FAQ
Are Core Web Vitals a ranking factor?
They’re part of Google’s page experience signals, but relevance and content quality matter much more. Treat good vitals as a way to keep visitors, not a ranking shortcut.
Why do PageSpeed Insights lab scores differ from real-user data?
Lab tests simulate one device and connection. Field data comes from real Chrome users over the previous 28 days. When they disagree, the field data shows what your visitors actually experience.
My site has no field data. What then?
Low-traffic sites often don’t have enough Chrome user data. Use lab tests in PageSpeed Insights or Lighthouse as a guide and fix the issues they flag.
Search engines update their systems and documentation often. This guide reflects Google’s published guidance at the time of writing; check Google Search Central for current details, and test changes on a staging copy of your site before making them live.