Core Web Vitals Score Checker
Google rates a page on three real-user metrics — how fast it loads, how quickly it responds, and how much it visually jumps. Enter your numbers and see exactly where you stand, metric by metric.
Core Web Vitals are three field metrics: LCP (loading, good at ≤2.5s), INP (responsiveness, good at ≤200ms) and CLS (visual stability, good at ≤0.1). A URL is rated good only when all three pass at the 75th percentile of real visits — the worst metric sets your verdict, so one weak number fails the whole page.
Core Web Vitals Score Checker inputs and result
| Metric | Your value | Good | Poor | Result |
|---|
How to use this calculator
- Pull your field valuesGet LCP, INP and CLS from the Chrome User Experience Report (CrUX) or PageSpeed Insights — use the field data (real visitors), not the lab score, since Google ranks on field data.
- Enter all three metricsType your 75th-percentile LCP in seconds, INP in milliseconds and CLS as a decimal. The 75th percentile means three in four visits are at least this fast.
- Read each metric's bandThe table shows whether each metric is good, needs improvement or poor against Google's published thresholds.
- Check the overall verdictRemember the rule: all three must pass for the page to count as good. Your verdict reflects the worst of the three.
- Fix the worst offender firstUse the analysis to prioritise. Export the result to share the diagnosis with your engineering team.
RGM Expert Says
We reach for this check at the start of any speed or technical-SEO engagement, because clients almost always quote a single lab score from PageSpeed Insights and treat it as gospel. The score that affects rankings and revenue is the field data — what real Chrome users experienced over the last 28 days — and it is reported per-metric, not as one tidy number. Separating the three metrics is usually the first thing that changes the conversation.
The all-three-must-pass rule is the part teams underestimate. A site can have a beautiful LCP and a clean CLS and still fail every audit because INP sits at 380 milliseconds from a bloated tag manager. We use this tool to isolate which metric is actually losing, so engineering effort goes to the bottleneck instead of being sprinkled across all three. More often than not the fix is removing third-party JavaScript, not shaving another image.
Where it pays off commercially is the link to conversion. A page that fails INP feels sluggish on the exact taps that matter — add-to-cart, checkout, form submit — and that friction shows up in funnel drop-off long before it shows up in rankings. We pair this score with our page-speed impact and funnel drop-off tools so a technical finding lands as a revenue argument the business will fund.
How it works
Each metric is graded against two thresholds into three bands — good, needs improvement, and poor. Google's rule is strict: a URL is classed as having good Core Web Vitals only when all three pass, so the overall verdict equals the worst of the three.
- LCP — Largest Contentful Paint, seconds. Good ≤ 2.5, poor > 4.0.
- INP — Interaction to Next Paint, milliseconds. Good ≤ 200, poor > 500.
- CLS — Cumulative Layout Shift, unitless. Good ≤ 0.10, poor > 0.25.
Thresholds and the ‘all three must pass at the 75th percentile’ rule are published by Google on web.dev and the Google Search Central docs.
Why one weak metric fails the whole page
Core Web Vitals are part of Google's page-experience signals, and they are measured on real users, not a lab simulation. That is why your PageSpeed Insights lab score and your field score can disagree: the lab runs one throttled load on one device, while the field data summarises thousands of real visits at the 75th percentile. Optimise for the field data, because that is what feeds Search.
The strict all-three-must-pass rule exists because a good experience is multi-dimensional. A page can paint fast yet feel broken if it jumps around as it loads (high CLS) or stalls when you tap a button (high INP). Treating the three together stops teams from gaming a single number while the experience stays poor.
INP is the metric most sites now fail. It replaced First Input Delay as a Core Web Vital in March 2024 and is far less forgiving, because it measures the slowest interactions across the whole visit, not just the first. Heavy JavaScript, oversized event handlers and chatty tag managers are the usual culprits.
Google's Core Web Vitals thresholds
These are the official cut-offs, assessed at the 75th percentile of real-user page loads. Hit the good column on all three to pass.
| Metric | Good | Needs improvement | Poor |
|---|---|---|---|
| LCP (loading) | ≤ 2.5 s | 2.5 – 4.0 s | > 4.0 s |
| INP (responsiveness) | ≤ 200 ms | 200 – 500 ms | > 500 ms |
| CLS (visual stability) | ≤ 0.10 | 0.10 – 0.25 | > 0.25 |
What measurement leaders say
What gets measured against real users gets fixed; lab scores flatter you, field data tells the truth about the experience people actually had.
Speed is a feature, and the slowest interaction a user hits is the one they remember — so optimise the tail, not the average.