---
title: Core Web Vitals monitoring
description: A performance regression rarely announces itself; it lands in a deploy and shows up weeks later as a worse search ranking. You can now monitor Core Web Vitals…
canonical: https://watchfor.io/changelog/2026-05-29-core-web-vitals-monitoring
---

[All updates](/changelog/page/9#2026-05-29-core-web-vitals-monitoring) ✨ New May 29, 2026 · v 2.8.2

# Core Web Vitals monitoring

A performance regression rarely announces itself; it lands in a deploy and shows up weeks later as a worse search ranking. You can now monitor Core Web Vitals (LCP and CLS, plus lab metrics such as Total Blocking Time) with a Lighthouse performance score, choose a desktop or mobile profile, and get alerted when scores regress. Not sure yet? The free Core Web Vitals checker lets you try it on any URL instantly.

Scores and a screenshot from the latest audit.

Trends over the week and the fixes worth doing first.

## What each audit measures

Each check loads your page in a real browser and runs a full Lighthouse audit:

- Core Web Vitals : Largest Contentful Paint (LCP) and Cumulative Layout Shift (CLS).

- Lab metrics : First Contentful Paint, Total Blocking Time, Time to Interactive and Speed Index.

- Scores from 0 to 100 for Performance, Accessibility, SEO and Best Practices.

- Evidence : a screenshot, a loading filmstrip, the top fixes with their estimated savings, a 7-day trend and the full Lighthouse report.

## Alerts

LCP (4 seconds) and CLS (0.25) are on, at Google's Poor boundaries. Performance Score and SEO Score are optional.

## Example

A new hero video ships on Tuesday. On Wednesday the homepage audit shows LCP at 4.6 seconds and an incident opens. The filmstrip shows the video taking two seconds to start, and the top fix suggests a smaller poster image.

## Try it

Audit any URL once with the free [Core Web Vitals checker](/core-web-vitals-checker), then create a Core Web Vitals monitor. See [Core Web Vitals](/docs/monitors/performance#core-web-vitals-browser).

Since then: a day later you could choose a desktop or a mobile profile per monitor. The launch also showed an Interaction to Next Paint tile and rule; a scheduled audit has no real visitors clicking, so it can't measure INP, and both were retired in September. Total Blocking Time is the lab stand-in.

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Canonical page: https://watchfor.io/changelog/2026-05-29-core-web-vitals-monitoring · Site guide: https://watchfor.io/llms.txt