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Shopify Page Speed Checker

Real Core Web Vitals from Google's PageSpeed Insights API. Same numbers Google uses for ranking.

Improving Shopify Core Web Vitals

  • • Audit apps first — on Shopify, third-party app JS is almost always the biggest bottleneck. The Lighthouse “Reduce third-party impact” opportunity will name them.
  • • Compress source images before upload — the CDN handles WebP, but starts from your original file.
  • • Use an Online Store 2.0 theme — older third-party themes are often the cause of CLS regressions.
  • • Reserve space for late-loading elements like sticky banners and image carousels to prevent CLS.
  • • Pair this tool with our Shopify site speed guide for the full diagnose-then-fix workflow.

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Frequently asked questions

Where do these numbers come from?

This tool calls Google's official PageSpeed Insights API and shows you the raw results. The lab metrics come from a Lighthouse run on Google's servers; the field metrics (Core Web Vitals) come from the Chrome User Experience Report — real-user data Google collects from Chrome. These are the same numbers Google uses to evaluate your site for ranking.

Why does it say "no field data" for some URLs?

CrUX only includes URLs that get enough Chrome traffic for a statistically meaningful sample. New stores, low-traffic pages, and most internal subpages will not have field data. In that case the lab metrics from Lighthouse are still useful as a directional indicator.

What are LCP, INP, and CLS?

LCP (Largest Contentful Paint) is how long the largest visible element takes to render. INP (Interaction to Next Paint) is how long the page takes to respond to taps and clicks — it replaced FID as a Core Web Vital in March 2024. CLS (Cumulative Layout Shift) is how much the page jumps around as it loads. Google targets: LCP under 2.5s, INP under 200ms, CLS under 0.1.

Why is the lab score different from the field score?

Lab results are a single simulated run on Google's servers with a throttled mobile profile. Field results are aggregated from real Chrome users with their own devices and network conditions. Field data is what Google uses for ranking. The two often differ — especially for stores with many app scripts that behave differently for real users than in a clean lab environment.

How can I improve my Shopify Core Web Vitals?

On Shopify specifically, the biggest lever is almost always app JavaScript — audit your installed apps and remove anything you do not actively use. Next: compress source images before upload (the Shopify CDN cannot fix 8MB camera files for you). Then: pick a modern Online Store 2.0 theme. See our Shopify site speed guide for the full diagnose-then-fix workflow.

Is this tool free?

Yes. No signup. The rate limit is 5 PageSpeed checks per minute per IP to stay within Google's API quota. For unlimited bulk testing, use the official PageSpeed Insights tool directly.

For the full Google interface with historical CrUX trends, go to pagespeed.web.dev .

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