SEO Tools
Core Web Vitals Checker
Grade LCP, INP, CLS, FCP, and TTFB against Google's official Core Web Vitals thresholds. Per-metric verdicts, page pass or fail, fix tips, no signup.
Core Web Vitals checker
Presets
Try a sample page result
Drop in a shape (passing, mixed, failing, or slow server) and see what the verdicts look like before entering your own numbers.
Your numbers
Enter your Core Web Vitals
Paste 75th-percentile values from PageSpeed Insights, the Chrome User Experience Report, Search Console, or a real-user monitor. Time metrics are in milliseconds; CLS is a unitless score (0.00 to about 1).
Largest Contentful Paint LCP
Time until the largest image or text block in the viewport finishes rendering.
Good at or below 2.5 s, Poor above 4.0 s.
Interaction to Next Paint INP
Worst input-to-next-paint latency across all interactions on the page (replaces FID since March 2024).
Good at or below 200 ms, Poor above 500 ms.
Cumulative Layout Shift CLS
Sum of unexpected layout shift scores during the page lifecycle.
Good at or below 0.10, Poor above 0.25.
First Contentful Paint FCP
Time until the first text, image, or non-white pixel is painted.
Good at or below 1.8 s, Poor above 3.0 s.
Time to First Byte TTFB
Time from navigation start to the first byte of the document response.
Good at or below 800 ms, Poor above 1.8 s.
Page Core Web Vitals verdict
Page passes Core Web Vitals
A page passes Core Web Vitals only when LCP, INP, and CLS are all Good at the 75th percentile of real-user page loads. Supplemental metrics (FCP, TTFB) do not affect the verdict but help diagnose the cause.
Metric breakdown
Every entered value graded against the official thresholds. Supplemental metrics are shown for context but do not change the page verdict.
| Metric | Type | Your value | Good | Poor | Rating |
|---|---|---|---|---|---|
Largest Contentful Paint LCP | Core | 2.50 s | ≤ 2.5 s | > 4.0 s | Good |
Interaction to Next Paint INP | Core | 200 ms | ≤ 200 ms | > 500 ms | Good |
Cumulative Layout Shift CLS | Core | 0.100 | ≤ 0.10 | > 0.25 | Good |
First Contentful Paint FCP | Supplemental | 1.80 s | ≤ 1.8 s | > 3.0 s | Good |
Time to First Byte TTFB | Supplemental | 800 ms | ≤ 800 ms | > 1.8 s | Good |
What to fix first
Recommendations ordered by impact for the metrics currently failing or marginal. Each row maps directly to the entry you graded above.
Every entered metric is already in the Good band. Keep monitoring your 75th-percentile field data after each release because lab numbers and field numbers can diverge.
Threshold reference
Official thresholds from web.dev/vitals. Numbers are measured at the 75th percentile of all real-user page loads in a 28-day window.
Largest Contentful Paint LCP
Core
- Good: ≤ 2.5 s
- Needs improvement: between 2.5 s and 4.0 s
- Poor: > 4.0 s
Time until the largest image or text block in the viewport finishes rendering.
Interaction to Next Paint INP
Core
- Good: ≤ 200 ms
- Needs improvement: between 200 ms and 500 ms
- Poor: > 500 ms
Worst input-to-next-paint latency across all interactions on the page (replaces FID since March 2024).
Cumulative Layout Shift CLS
Core
- Good: ≤ 0.10
- Needs improvement: between 0.10 and 0.25
- Poor: > 0.25
Sum of unexpected layout shift scores during the page lifecycle.
First Contentful Paint FCP
Supplemental
- Good: ≤ 1.8 s
- Needs improvement: between 1.8 s and 3.0 s
- Poor: > 3.0 s
Time until the first text, image, or non-white pixel is painted.
Time to First Byte TTFB
Supplemental
- Good: ≤ 800 ms
- Needs improvement: between 800 ms and 1.8 s
- Poor: > 1.8 s
Time from navigation start to the first byte of the document response.
How the verdict works
Google judges a page on Core Web Vitals using LCP, INP, and CLS only. To pass, all three must land in the Good band at the 75th percentile of real-user field data. A single metric in the Poor band drops the whole page to Poor; any metric in Needs improvement (and none in Poor) drops the page to Needs improvement.
FCP and TTFB are reported alongside the Core Web Vitals in PageSpeed Insights and Search Console but do not directly drive the page-experience ranking signal. They are useful for diagnosing why the core trio is slow: a high TTFB explains a high LCP, and a high FCP usually means the critical request needs trimming. INP replaced FID as the responsiveness Core Web Vital in March 2024; FID is now retired.
Numbers in this tool match Google's published thresholds. They run entirely in your browser. Nothing you type here is uploaded.
How to use
- Click a preset (Page passes, Mixed result, Needs work, Slow server) to see what each verdict looks like, or skip to the inputs.
- Enter the 75th-percentile values for LCP, INP, and CLS (the three Core Web Vitals). Add FCP and TTFB if you have them. Times are in milliseconds; CLS is a unitless decimal.
- Read the per-metric verdict next to each input and the overall page verdict in the headline card. The page passes only when LCP, INP, and CLS are all Good.
- Open the fix-first panel for concrete remediation steps on any metric in Needs improvement or Poor.
- Use Copy report to grab a plain-text summary for a PR comment, a Slack thread, or a performance audit log.
About this tool
Core Web Vitals Checker grades the five metrics Google reports for page experience against the official thresholds from web.dev/vitals. The three Core Web Vitals (LCP, INP, CLS) directly drive Google's page-experience ranking signal; FCP and TTFB are supplemental Web Vitals shown alongside in PageSpeed Insights, Search Console, and most real-user monitors. Type the 75th-percentile value for each metric and the tool returns a Good, Needs improvement, or Poor verdict per metric, plus the overall page verdict using Google's rule that a page passes only when LCP, INP, and CLS are all Good. INP (Interaction to Next Paint) replaced FID (First Input Delay) as the responsiveness Core Web Vital in March 2024 and is what Google measures today. A visual threshold ladder shows where each value lands between the Good and Poor cutoffs, the metric breakdown table lists every threshold side by side, the fix-first panel suggests concrete remediation for any metric in Needs improvement or Poor, and a copy-ready plain-text report is ready to paste into a Slack thread, a PR comment, or an audit log. Useful for SEO specialists checking whether a page passes Core Web Vitals after a redesign, performance engineers triaging which metric to fix first, developers translating PageSpeed Insights numbers into a clear verdict, agencies reporting page-experience scores to clients, and site owners reading their Search Console Core Web Vitals report. Everything runs in your browser; the numbers you type are never uploaded.
Free to use. Works in your browser. No signup, no login.
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