# Core Web Vitals

> Source: https://rankxai.com/glossary/core-web-vitals · Last updated: 2026-08-18

Core Web Vitals are Google’s three measurements of real-user page experience: Largest Contentful Paint for loading, Interaction to Next Paint for responsiveness, and Cumulative Layout Shift for visual stability. Core Web Vitals are assessed at the 75th percentile of real page loads, not in a lab test.

## What are the current thresholds?

Three metrics, three bands each, measured at the 75th percentile of real page loads and segmented across mobile and desktop. Interaction to Next Paint replaced First Input Delay as a stable Core Web Vital in 2024, so any guide still listing FID is out of date.

Core Web Vitals thresholds from Google’s web.dev documentation, read 18 August 2026.

- Metric: Largest Contentful Paint. Good: 2.5 seconds or less. Poor: over 4.0 seconds
- Metric: Interaction to Next Paint. Good: 200 ms or less. Poor: over 500 ms
- Metric: Cumulative Layout Shift. Good: 0.1 or less. Poor: over 0.25

## How much do Core Web Vitals affect rankings?

Less than the attention they get, and the honest shape is asymmetric. Moving a page out of the poor band can matter in a close contest; polishing a page that is already good measures close to nothing. Sites without enough real-user data in Google’s dataset get no page-experience signal at all, which quietly exempts most small sites from the whole discussion. The measurement itself is often misread as well. These are field metrics from real visitors over a rolling window, not a laboratory score, so a synthetic test result is a diagnostic rather than the number Google uses.

A page can score badly in a lab tool and pass in the field, and the reverse happens too. The gap is usually caching and device mix: a lab test runs cold on one simulated phone, while your real visitors arrive with warm caches on a range of hardware. Both numbers are worth having for different jobs: the lab result tells you what changed after a deploy, and the field data tells you what your visitors actually experienced.

## Do Core Web Vitals affect AI citations?

There is no evidence that they do, and there is a mechanism suggesting they mostly cannot. AI crawlers fetch HTML and do not render it: Vercel’s network analysis found the major AI crawlers requesting JavaScript and executing none of it. Layout shift and interaction latency are properties of a rendered page that no AI crawler ever produces.

What survives is the underlying reason to care. A page slow enough to time out a fetch is a page that does not get collected, and the JavaScript you do not ship cannot break either your interaction score or your visibility. Speed is worth pursuing for users and for revenue, and claiming a citation benefit for it is inventing one.

## Sources

- [Google web.dev: Web Vitals, with current thresholds and percentile](https://web.dev/articles/vitals), checked 2026-08-18
- [Vercel: the rise of the AI crawler, 17 December 2024](https://vercel.com/blog/the-rise-of-the-ai-crawler), checked 2026-08-18