> ## Documentation Index
> Fetch the complete documentation index at: https://help.get-ryze.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Core Web Vitals

> Core Web Vitals are Google's three metrics for page experience: Largest Contentful Paint, Interaction to Next Paint, and Cumulative Layout Shift.

Core Web Vitals are Google's three metrics for measuring real-world page experience: **Largest Contentful Paint (LCP)**, **Interaction to Next Paint (INP)**, and **Cumulative Layout Shift (CLS)**.

They are measured from real user data, not lab tests, and a URL must meet all three thresholds to pass.

## The three metrics

| metric  | measures                                         | good    | needs work | poor    |
| ------- | ------------------------------------------------ | ------- | ---------- | ------- |
| **LCP** | time until the largest visible element renders   | ≤ 2.5s  | 2.5–4.0s   | > 4.0s  |
| **INP** | latency from user interaction to visual response | ≤ 200ms | 200–500ms  | > 500ms |
| **CLS** | unexpected visual movement during load           | ≤ 0.1   | 0.1–0.25   | > 0.25  |

Thresholds are assessed at the **75th percentile** of page loads, segmented by mobile and desktop. Passing means 75% of real visits met the threshold — not the average.

INP replaced First Input Delay as a Core Web Vital in March 2024. FID measured only the delay before the first interaction was processed; INP measures the full interaction-to-paint latency across all interactions on the page.

## Common causes on ecommerce sites

**LCP** — unoptimised hero and product imagery, render-blocking CSS or fonts, slow server response, oversized image dimensions served to mobile.

**INP** — heavy third-party scripts (chat widgets, analytics, review platforms, A/B testing tools), long JavaScript tasks blocking the main thread, unoptimised event handlers on filters and variant pickers.

**CLS** — images and embeds without explicit dimensions, banners and cookie notices injected above existing content, web fonts causing layout reflow, dynamically inserted promotional bars.

## How they are measured

* **Field data** — the Chrome User Experience Report (CrUX), based on real Chrome visits over a rolling 28-day window. This is what Google uses for assessment.
* **Lab data** — Lighthouse and PageSpeed Insights simulations. Useful for diagnosis, but does not directly determine the assessment.

Because field data uses a 28-day rolling window, fixes take weeks to show up fully.

## Weight in ranking

Core Web Vitals are a genuine but small ranking signal. Relevance and content quality dominate. They matter most as a tiebreaker between comparably relevant pages — and independently for conversion, since slow pages lose buyers regardless of ranking.

## Primary references

* [Core Web Vitals — web.dev](https://web.dev/articles/vitals)
* [Google page experience documentation](https://developers.google.com/search/docs/appearance/page-experience)

## Related

* [Technical SEO](/concepts/technical-seo)