Free AI visibility report

Get my report
RANKBULL

Core Web Vitals Checker

Test any page with Google PageSpeed Insights: LCP, INP and CLS from real Chrome users, lab scores, and the fixes that matter most, on mobile and desktop.

  • Free, no signup
  • Results in seconds
  • Works for Shopify stores

Runs Google PageSpeed Insights. Takes 20–40 seconds. Start with mobile: it's what Google ranks.

You'll see whether the page passes Google's Core Web Vitals (LCP, INP and CLS) for real Chrome visitors, a lab score, and the fixes that would save the most time.

Why Core Web Vitals matter for your business

Core Web Vitals are Google's measures of how a page feels to real visitors: how fast the main content appears, how quickly the page reacts when someone taps, and whether it jumps around while loading. They're part of how Google judges page experience, and they measure exactly the kind of frustration that makes a shopper give up and go back to search.

They come from your real visitors
Google collects Core Web Vitals from Chrome users who visit your site and publishes them in the Chrome UX Report. That field data, not a one-off test, is what Google uses, which is why this checker shows it first when it exists.
Speed is a tiebreaker, not a shortcut
Google has said that relevance comes first: a slower page with the best answer can still rank. Between two similarly helpful pages, a better page experience gives you the edge, and it keeps the visitors you already earned.
Mobile is the version that counts
Google indexes the mobile version of your site, and most small business and store traffic comes from phones, where heavy scripts hurt the most. Test mobile first, then desktop.
Most fixes are smaller than you think
The biggest wins are usually one oversized image, a couple of unused apps or a slow-loading font. The fix list is sorted by estimated time saved, so you can start with the change that matters most.

How to use the Core Web Vitals Checker

  1. Enter a page

    Type your domain, like yourstore.com, or paste a specific page such as a product, collection or service page. You don't need to add https://.

  2. Pick mobile or desktop

    Start with mobile. You can switch to desktop afterwards, and each device's result is kept, so flipping back is instant.

  3. Wait for Google's test

    The test runs on Google PageSpeed Insights and usually takes 20 to 40 seconds, because Google really loads your page on its servers and measures it.

  4. Fix from the top, then re-test

    Read the verdict, then work down "What to fix first". Once a change is live, test again to confirm it in the lab score; real-visitor data takes a few weeks to catch up.

Core Web Vitals thresholds

Google judges each metric at the 75th percentile of real visits: at least three out of four visits need to be in the good range. A page passes Core Web Vitals when LCP, INP and CLS are all good. First Input Delay (FID) is no longer used; INP replaced it in March 2024.

MetricWhat it measuresGoodNeeds workPoor
LCP (Core Web Vital)How fast the biggest image or text block appears2.5 s or less2.5–4 sOver 4 s
INP (Core Web Vital)How fast the page visibly reacts to taps, clicks and typing200 ms or less200–500 msOver 500 ms
CLS (Core Web Vital)How much the layout jumps while loading0.1 or less0.1–0.25Over 0.25
FCPWhen the first text or image appears1.8 s or less1.8–3 sOver 3 s
TTFBHow fast the server starts sending the page0.8 s or less0.8–1.8 sOver 1.8 s
TBT (lab only)How long scripts freeze the page during the lab test200 ms or less200–600 msOver 600 ms

What usually causes each problem

  • Slow LCP

    Usually an oversized hero image or slider, a slow server, or scripts and fonts that block the page from painting. Compress the first image, don't lazy-load it, and cut render-blocking scripts.

  • Poor INP

    Almost always too much JavaScript: chat widgets, pop-ups, review and upsell apps, trackers and heavy themes all compete for the phone's processor. Remove what you don't need and delay the rest until after the page loads.

  • High CLS

    Images and embeds without a set width and height, banners or cookie notices that push content down, and web fonts that swap in late. Reserve space for anything that loads after the first paint.

Questions about the Core Web Vitals Checker

Core Web Vitals are three Google metrics for real-world page experience: Largest Contentful Paint (LCP) for loading, Interaction to Next Paint (INP) for responsiveness, and Cumulative Layout Shift (CLS) for visual stability. A page passes when, for at least 75% of visits, LCP is 2.5 seconds or less, INP is 200 milliseconds or less and CLS is 0.1 or less.

Interaction to Next Paint (INP) replaced First Input Delay as a Core Web Vital in March 2024, and FID is no longer used. INP is stricter: FID only measured the delay before the first tap was handled, while INP looks at how long the page takes to visibly respond to taps, clicks and key presses throughout the whole visit. Heavy JavaScript is the usual cause of a poor INP.

Field data is what real Chrome visitors experienced over the last 28 days; lab data is one simulated page load that Google runs when you start the test. Google uses field data to judge your site, so trust it when the two disagree. Lab data is repeatable, which makes it useful for checking a fix before real-visitor data catches up. The lab test can't measure INP because nobody taps anything, so it shows Total Blocking Time instead.

Google only publishes field data for pages and sites with enough Chrome visits to be reliable, so new, small or low-traffic sites often have none. That's normal and isn't a penalty. When a single page doesn't qualify, the checker shows data for your whole site if Google has it, and otherwise it bases the verdict on the lab test.

It can help, but it's rarely the biggest factor. Google uses page experience signals, including Core Web Vitals, alongside many others, and content that best answers the search matters more. Moving from poor to good is worth doing for both rankings and sales; chasing a perfect lab score of 100 usually isn't.

Apps and theme scripts are the most common cause. Review widgets, pop-ups, live chat, upsell and tracking apps each add JavaScript that loads on every page, and uninstalled apps can leave code behind in your theme. Large hero images and sliders slow down LCP too. Remove apps you don't use, check theme files for leftover snippets, and compress the first image on the page.

Lab scores vary a little from run to run because network and server timing vary, so a swing of a few points is normal. Field data moves slowly because it covers 28 days of visits, so it can take a few weeks after a fix to show the full improvement. Recent results for the same page may be reused for a few hours, so re-test later to see a change.

Yes, it's free with no signup. It runs Google's own PageSpeed Insights test and explains the results in plain English, with fixes sorted by impact. The test only reads your public page; nothing on your site is changed.

Fast pages still need to be the answer.

RankBull publishes lightweight, well-structured articles and tracks whether Google and AI engines recommend them.

See plans from $29/moGet the Shopify app

On Shopify, the results show which apps and theme scripts slow your storefront down.

Free AI visibility report for your site

Free · no card · verbatim engine answers · graded fixes

More free tools