Shopify speed test

What the speed test checks

Enter any page of a Shopify store. The test first confirms the site runs on Shopify and which theme it uses, then runs four checks:

• Lighthouse lab test: Google PageSpeed Insights loads the page once on a simulated phone and once on desktop, and scores it from 0 to 100.
• Real-user Core Web Vitals: 28 days of Largest Contentful Paint, Interaction to Next Paint and Cumulative Layout Shift from Chrome users when enough data is available, for the page or, with less traffic, the whole site. Missing data is not a pass or a fail.
• What slows it down: the apps, scripts, images and theme code with the largest estimated savings, with the change that fixes each one.
• Headless estimate: how much of the measured saving a fix on your current theme could deliver, against what only a custom storefront would change, with the assumptions listed.

A test takes 10 seconds to 2.5 minutes, because Google loads the page in a real browser. Results are saved for 24 hours, so testing the same page again shows the saved result.

What is a good Shopify speed score?

A good Shopify speed score is a pass on Core Web Vitals from real visitors on phones. Lighthouse rates a lab score of 90 to 100 as good, but that comes from one simulated visit, so use it to find causes rather than as the goal.

To see how other Shopify stores do, our Shopify speed study reads Chrome’s real-user data every month. It covers stores with enough phone visits for Chrome to measure: 449,762 Shopify stores in October 2026.

• 82% of the Shopify stores Chrome could judge passed Core Web Vitals on phones, against 66% of all judged online stores.
• The median measured Shopify store showed its main content in 1.4 s, against 1.8 s across measured online stores.
• 90% of measured Shopify stores showed their main content within 2.5 s, against 72% of measured online stores.
• Busier stores passed less often: 51% of judged Shopify stores among the 100,000 most-visited sites passed.

Run the test above and compare your store’s real-user results with these figures. The study counts whole stores, not single pages, so compare them with the whole-site result when the report shows one. When Chrome has too little tap data for Interaction to Next Paint, the study judges a store on Largest Contentful Paint and Cumulative Layout Shift alone, so a store passes there on two measures rather than three.

Source: Skai’s analysis of Chrome UX Report data for October 2026, phone visits at the 75th percentile, with platforms detected by HTTP Archive.

What your Shopify speed score means

The Lighthouse score comes from one simulated visit on a mid-range phone with a throttled connection. It's good for finding causes and comparing changes, but it moves from run to run.

Lighthouse rates 90–100 as good, 50–89 as needs improvement and 0–49 as poor. These are lab scores, not search rankings. Google uses Core Web Vitals in its ranking systems alongside many other signals; a good score does not guarantee a higher ranking.

Core Web Vitals pass when the 75th-percentile Largest Contentful Paint is within 2.5 seconds, Interaction to Next Paint within 200 milliseconds and Cumulative Layout Shift at most 0.1. All three need enough real-user data to establish a pass. Whole-site data is not proof that this specific page passes, and a low lab score can coexist with good real-user results.

Why Shopify stores get slow

Shopify serves pages and images from a fast global network, so most slowness is added on the store itself:

• Apps that add scripts to every page, such as reviews, chat, upsells, analytics and tag managers. Removing an app can leave its code in the theme.
• Large images without a width that matches the layout, especially in the first screen.
• Theme JavaScript for sliders, page builders and inline scripts that delays interaction.
• Fonts and banners that move the page as they load.

Most of these are fixed on the current theme. Our Shopify speed optimization service starts from real-user measurement and keeps measuring after each change.

How the headless estimate works

A headless storefront replaces the theme's HTML, JavaScript and app embeds with code you control. That only pays off on speed when the theme's own code is the bottleneck. If apps and images cause most of the delay, a rebuild that adds the same scripts back won't be faster.

The report groups Lighthouse opportunities into changes you can make on your current theme and architectural changes a custom storefront could address. Savings can overlap; they are not additive, a predicted future score or a guarantee of faster real-user visits. The report lists its assumptions. For stores already running headless, the theme-to-headless estimate is skipped; the lab results and available real-user data still apply.

See our Kastel storefront and measurement work and Epivity subscription storefront for delivered examples, not forecasts for your store. For the wider trade-offs, read how to choose a headless Shopify agency or see our headless Shopify agency work.

Use it in your AI tools

The same speed test runs as a free MCP server at https://tools.skaidigital.com/mcp, with no account or key. AI assistants that support remote MCP servers can check a store's speed, detect whether it runs on Shopify, and compare Shopify plan fees.

Add to CursorInstall in VS Code

Use the install links or copy the configuration below. In Claude Desktop, add the remote URL through Settings → Connectors → Add custom connector if your version supports it; the remote JSON is shown below for clients that accept it. Clients without remote support can use npx mcp-remote https://tools.skaidigital.com/mcp (requires Node.js). Source of the config and manifests on GitHub.

claude mcp add --transport http shopify-speed-check https://tools.skaidigital.com/mcp

{
  "mcpServers": {
    "shopify-speed-check": {
      "url": "https://tools.skaidigital.com/mcp"
    }
  }
}

{
  "servers": {
    "shopify-speed-check": {
      "type": "http",
      "url": "https://tools.skaidigital.com/mcp"
    }
  }
}

{
  "mcpServers": {
    "shopify-speed-check": {
      "url": "https://tools.skaidigital.com/mcp"
    }
  }
}

{
  "mcpServers": {
    "shopify-speed-check": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-remote",
        "https://tools.skaidigital.com/mcp"
      ]
    }
  }
}

Frequently asked questions

Is the Shopify speed test free?

Yes. There is no sign-up. A fair-use limit per visitor keeps it free for everyone, and results are saved for 24 hours.

Why is my Shopify PageSpeed score so low on mobile?

The mobile test simulates a mid-range phone on a throttled connection, so heavy scripts and large images cost far more than on desktop. Check the available real-user Core Web Vitals too: they reflect Chrome visits rather than a single lab run and are one of the signals Google uses.

What is a good Shopify speed score?

A pass on Core Web Vitals from real visitors on phones. Of the Shopify stores Chrome had enough data to judge in October 2026, 82% passed on phones, against 66% of all judged online stores. The median measured Shopify store showed its main content in 1.4 s. Our Shopify speed study has the full figures, updated every month.

What is a good PageSpeed score for a Shopify store?

Lighthouse rates 90 to 100 as good, 50 to 89 as needs improvement and under 50 as poor. For search, passing Core Web Vitals with real users matters more than the lab score.

Which apps slow down a Shopify store?

Any app that loads scripts on every page can. The report names the apps and third-party scripts with the most main-thread work and download size on your store, so you can see which ones cost the most.

Does the speed test work on headless and Hydrogen stores?

Yes. It detects Hydrogen and Oxygen storefronts, and storefronts on other hosts that load Shopify assets. The theme-to-headless estimate is skipped for stores already running headless; lab scores and available real-user Core Web Vitals still appear.

Will going headless make my Shopify store faster?

Only if the theme's own code is what slows it down. The report's headless estimate compares the savings you can make on your current theme with those only a custom storefront would change.

Does a low PageSpeed score hurt my Google rankings?

A low Lighthouse score does not directly determine your Google ranking. Core Web Vitals is one page-experience signal; relevance matters far more. Passing Core Web Vitals is useful, but it does not guarantee a ranking improvement.

Do you store my store's data?

We store the domain, detected platform and theme, and scores for 24-hour caching, not IP addresses. Rate limiting uses a keyed hash. The test needs no Shopify login or customer data. The public URL is sent to Google PageSpeed Insights and the Chrome UX Report; do not include private tokens or customer information in the address.

Can I run the speed test from ChatGPT, Claude or Cursor?

Yes, from any assistant that supports remote MCP servers. Add https://tools.skaidigital.com/mcp; it needs no account or key.