Report analyzer · browser-local

Core Web Vitals Checker

Q: Does this checker test my URL?

No. It analyzes measured values that you enter or JSON that you paste in your browser. Open the official PageSpeed Insights tool to test a URL, then copy the displayed field values and their context here.

Q: What counts as good Core Web Vitals?

The good thresholds are LCP at most 2,500 ms, INP at most 200 ms, and CLS at most 0.1. All three supplied field p75 values must meet those thresholds for this analyzer to report that all are good.

Q: Why is INP unavailable in my Lighthouse report?

A Lighthouse navigation run has no real user interactions to measure INP. Total Blocking Time is a lab diagnostic, not an INP measurement, so this checker never substitutes it.

Q: Why does my field report have missing data?

CrUX may not have sufficient eligible observations for the page or metric. Missing data is not a zero or a pass. The analyzer keeps missing metrics unavailable and does not combine URL values with origin values.

Q: Which report formats can I paste?

Supported inputs are PSI JSON with loadingExperience, originLoadingExperience or lighthouseResult; a standalone Lighthouse JSON report with audits; and a CrUX response with record.metrics. For a visual PSI report, use manual entry. Do not paste HTML or a report link.

Assess measured LCP, INP and CLS from your report. This browser-local tool does not fetch or measure a website.

Obtain measurements in PageSpeed Insights ↗

Your assessment will appear here

Enter measured values. A blank metric remains unavailable.

Read the evidence

Three metrics, three different questions

A Core Web Vitals test examines loading, responsiveness and visual stability. Compare field values at the 75th percentile for a consistent device group. This analyzer applies thresholds to your supplied data; it does not verify report authenticity or freshness.

Keep the original report alongside your exported assessment. A lab run can help investigate a change immediately, while field data reflects visitors over a collection period. Neither a good result nor a performance score guarantees a search ranking.

LCP: when the largest visible content appears.

Responsiveness

INP: delay across observed interactions.

Stability

CLS: unexpected movement in page layout.

Provenance

Keep device, scope and collection dates together.

Read thresholds without losing context

LCP describes loading, INP describes interaction responsiveness, and CLS describes visual stability. Lower values are better. CLS is unitless.

Metric	Good	Needs improvement	Poor
LCP	≤ 2,500 ms	> 2,500–4,000 ms	> 4,000 ms
INP	≤ 200 ms	> 200–500 ms	> 500 ms
CLS	≤ 0.1	> 0.1–0.25	> 0.25

Threshold source: Google Web Vitals guidance.

Official PageSpeed Insights URL input and Analyze button — Start with the URL field on the official PageSpeed Insights site. This is its entry screen, not a measured result. After running a test there, transfer its field p75 values here.

01 · Keep field and lab separate

PageSpeed Insights presents real-user field information and a separate simulated lab run. CrUX field reports aggregate observations over a 28-day collection window. A fresh lab result does not replace that history. Record the dates and device before comparing two assessments.

02 · Check the scope

A URL report concerns one page. An origin report aggregates pages under the same origin. This importer presents each separately and never fills missing URL metrics with origin values. PSI field JSON may omit device and collection dates; check the original report when they are unavailable here.

03 · Turn a finding into an investigation

For slow loading, inspect the LCP element and its resource waterfall. For delayed interactions, profile the work triggered by an actual interaction. For layout shifts, identify the moving elements and missing reserved space. The values alone cannot identify a root cause.

Understand the source: About PageSpeed Insights · CrUX record formats and scope.