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Core Web Vitals Threshold Checker
The Core Web Vitals threshold checker grades the three metrics Google uses in its page experience signal — Largest Contentful Paint, Interaction to Next Paint, and Cumulative Layout Shift — against the exact Good, Needs improvement, and Poor limits Google publishes. Paste the field values from your PageSpeed Insights or CrUX report and each metric is colour-graded instantly, with an overall pass status that mirrors how Google evaluates a URL at the 75th percentile.
It is completely free and runs entirely in your browser, so the numbers you enter never leave the page. Because it grades values you already have rather than measuring your site, it works for staging URLs, competitor data, and offline reports alike, and the built-in page-weight budget helper turns a target transfer size into a per-resource allocation you can plan against.
Enter the field values from your PageSpeed Insights or CrUX report. The tool grades each metric against Google’s published thresholds. It checks numbers you provide — it does not measure your site.
🔒 Private: everything runs in your browser. Nothing you paste is uploaded.
A page-weight budget splits a target total transfer size across resource types. The percentages below are an editable planning model, not a measurement — adjust them to match your stack, then track real bytes against each line.
🔒 Private: everything runs in your browser. Nothing you paste is uploaded.
How to read your Core Web Vitals against Google’s thresholds
Enter the field values from a real-user report, read the badge for each metric, then use the budget tab to plan the transfer size that keeps LCP fast. The grading rules below are Google’s published thresholds, applied to numbers you supply.
Largest Contentful Paint: keep the main element under 2.5 seconds
LCP measures when the largest visible element — usually a hero image, heading, or video poster — finishes rendering. Google rates it Good at 2.5 seconds or less and Poor above 4.0 seconds, with the middle band needing improvement. The checker compares your entered value to those exact cut-offs. Most LCP problems trace back to slow server response, render-blocking resources, or an unoptimised hero asset, so the field value you paste here is the number to drive toward 2.5 seconds with faster hosting, preloading, and image compression.
Interaction to Next Paint: respond to taps within 200 milliseconds
INP replaced First Input Delay in March 2024 as the responsiveness vital. It records the slowest interaction across a visit, from tap to the next frame painted, and Google rates it Good at 200 milliseconds or less and Poor above 500 milliseconds. Enter the INP from your report and the tool flags which band it lands in. High INP almost always points to heavy JavaScript blocking the main thread, so breaking up long tasks, deferring non-critical scripts, and trimming third-party tags are the levers that move this metric back into the Good range.
Cumulative Layout Shift: hold the score at or below 0.1
CLS is a unitless score that sums unexpected layout movement while the page loads. Google rates it Good at 0.1 or less and Poor above 0.25. Because it has no unit, a small-looking number can still fail, which is why the checker grades the exact value rather than a rounded one. Layout shift usually comes from images and ads without reserved dimensions, late-loading fonts, or content injected above existing elements, so setting explicit width and height and reserving space for embeds keeps the score comfortably inside the Good band.
Core Web Vitals threshold checker frequently asked questions
Q1What are the current Core Web Vitals thresholds?
Google rates Largest Contentful Paint as Good at 2.5 seconds or less and Poor above 4.0 seconds, Interaction to Next Paint as Good at 200 milliseconds or less and Poor above 500 milliseconds, and Cumulative Layout Shift as Good at 0.1 or less and Poor above 0.25. This tool grades the values you enter against those published cut-offs.
Q2Does this tool measure my website’s speed?
No. It grades field values you already have, such as the numbers from a PageSpeed Insights or Chrome User Experience Report. Nothing is fetched or measured. That keeps it fully private and lets you check staging URLs, competitor data, or saved reports, but you still need a real measurement source to get the LCP, INP, and CLS values to paste in.
Q3Why does a URL need all three metrics to be Good to pass?
Google considers a page to pass the Core Web Vitals assessment only when LCP, INP, and CLS are all in the Good range at the 75th percentile of real visits. A single Poor or Needs improvement metric prevents the pass, so the overall status in this tool turns green only when every metric clears its Good threshold.
Q4Is the page-weight budget the same as Core Web Vitals?
No. The budget helper is a separate planning model that splits a target transfer size across HTML, CSS, JavaScript, images, and fonts. It is editable arithmetic, not a measurement, and lighter pages tend to load faster, which helps LCP. It is a guide for planning, not a guaranteed score, so treat the shares as a starting point and adjust them to your stack.
Q5What field value should I enter, lab or field data?
Prefer field data from real users, since that is what Google uses for the page experience signal at the 75th percentile. Lab numbers from a single synthetic run are useful for debugging but can differ from what visitors experience. When a report shows both, enter the field value to match how Google assesses the URL, and use lab data to diagnose what to fix.
