Since May 2021, Google uses Core Web Vitals as a ranking signal. Three user experience metrics that determine, in part, where your site appears in search results. If you haven’t optimized them, you’re losing positions to competitors who have.
What Core Web Vitals measure
These are three indicators Google collects from real users visiting your site (field data, not lab data):
LCP — Largest Contentful Paint
Measures how long it takes for the largest visual element on screen to load. It can be a hero image, a large text block or a video. Google wants it under 2.5 seconds. Above 4 seconds, your site is in the red zone.
INP — Interaction to Next Paint
Replaced FID in March 2024. Measures site responsiveness when the user interacts: clicks, taps, keyboard presses. Google’s threshold is under 200ms.
CLS — Cumulative Layout Shift
Measures the visual stability of the page. If elements move while it loads (images without dimensions, banners that appear late), CLS increases. Google wants less than 0.1.
How to check if your site has problems
The most direct way: Google Search Console → Experience → Core Web Vitals. You’ll see how many URLs are “Poor”, “Needs Improvement” or “Good”, with real data from Chrome users.
You can also use PageSpeed Insights (PSI) for individual URLs. Note: PSI shows both field data (CrUX) and lab data. For ranking purposes, what matters is field data.
The most common issues
- Images not compressed or converted to WebP
- Slow shared hosting with high TTFB
- WordPress themes with too many render-blocking scripts
- Google Fonts without preconnect
- Cookie banners poorly implemented that spike CLS
Do Core Web Vitals actually move rankings?
Yes, but with nuance. They’re a tiebreaker: when two pages have similar content quality, the one with better user experience wins. In competitive sectors, that tiebreaker can be the difference between position 3 and position 8.
In real projects, improving LCP from 5.8 to 1.9 seconds on an eCommerce site resulted in a 23% increase in average positions over 60 days — with no content changes.
Where to start
- Measure first: GSC → Core Web Vitals
- Prioritize high-traffic URLs in “Poor” status
- Attack LCP first (biggest impact on most sites)
- Optimize images, review hosting, eliminate render-blocking JS
- Validate improvements with PSI before confirming the issue is resolved