How themes are tested

What is measured

Every theme is tested on its own demo store — the storefront the vendor publishes to show the theme — with Google Lighthouse, run through the PageSpeed Insights API. That is the same engine behind Google's own PageSpeed report, and the numbers are the ones a merchant would get by pasting the demo's address into it.

• Three pages per preset on the store platforms — Shopify and BigCommerce demos are tested on the home page, a collection (category) page and a product page. WordPress, Squarespace, Wix, Framer and Astro demos are tested on the home page, which is what their marketplaces publish.
• Two devices: Lighthouse's simulated mid-range phone on a slow 4G connection (the mobile score) and a desktop profile. Mobile is the headline because it is what Google ranks by and what most shoppers use.
• Three categories on every ranking: speed (Lighthouse performance), SEO and accessibility, each 0–100 where 90 and above is good, 50–89 needs improvement and below 50 is poor. Best practices is recorded and shown on each theme's page.
• Core Web Vitals from the same run — Largest Contentful Paint, Cumulative Layout Shift, Total Blocking Time — plus the audits Lighthouse failed, so each theme's page says why a score is not 100 and how much effort the fix is likely to be.

Where the themes come from

The catalogue is read from the marketplaces themselves and refreshed continuously; a theme that disappears from its marketplace is delisted here. Presets (the vendor's alternative styles of the same theme) are tested individually.

12,137 themes and 13,032 presets have scores today, from 31,463 successful Lighthouse runs. The rest are queued; the pipeline status page shows the queue live.

How a theme's score is built

1. A page has one score per device and category: the latest successful run.
2. A preset is the mean of its pages, so a fast home page cannot hide a slow product page.
3. A theme is the median of its presets: the typical preset, unmoved by one showpiece or one neglected variant.
4. The preset range shown beside a theme is the lowest and highest speed score of any page of any preset, per device — the spread a merchant could land anywhere in.

Scores are never overwritten. Every run is kept, each theme's page and popup show the history, and the freshness column says when a theme was last measured. Themes are re-tested continuously, oldest first, so a vendor's update shows up without anyone asking.

What is excluded, and why

A perfect score on a page that is not a store is not a result. Before a page is tested, and again on every run, it is checked:

• Dead and placeholder demos — 404s, server errors, "store unavailable", password-protected storefronts, "coming soon" pages, responses too small to be a page, and demos that redirect to a different site. These pages are marked unavailable and drop out of the rankings until they come back. 388 of 21,804 verified demo pages are currently excluded this way.
• Runs that did not measure the demo — each run's final URL, host and page weight are compared with what a normal browser receives. A run that landed on another host, on a password page, or on far less than a browser is served is flagged and never counts. This is also the guard against cloaking: serving a stripped-down page to Lighthouse's user agent and the real one to everyone else. 175 runs are flagged today.
• PageSpeed errors — a run that fails inside Google's service is retried later and is not a score.

Demo realism

A demo is the vendor's choice of content, and the score is a score of that page. Two labels say when the demo is not a typical store:

• thin demo — the home page loads a fraction of what a stocked storefront does. The bar is per ecosystem, because a Shopify demo (median 3 MB, 220 requests) and a WordPress.org preview (median 440 KB, 20 requests) are different things: a Shopify or BigCommerce demo is thin under 400 KB or 15 requests, a Framer demo under 250 KB or 12 requests, a WordPress or Astro demo under 120 KB or 8 requests. A score earned on a near-empty page flatters the theme. 275 themes carry the label today.
• heavy demo — the home page loads more than 6 MB, heavier than most real stores; the score may understate the theme. 605 themes carry it.

Popularity and names

Where a marketplace publishes a usage signal it is used as the popular order and as the default order of each platform's landing page: review counts on the Shopify Theme Store, download counts on WordPress.org, sales on ThemeForest, all on a log scale with a small weight for the rating. Framer, Astro, Squarespace and Wix publish no such signal, so their landing pages open on speed. Popularity never changes a score.

Marketplace titles are marketing copy — "Goodwin - Ultimate Responsive Shopify Theme - Multipurpose OS 2.0" — and the theme's name is the first word or two. Rankings show the name; each theme's page also shows the full listing title.

Limits worth knowing

• A demo is not your store. Your apps, images, fonts and tracking scripts will move every number. The rankings compare themes on equal terms: what each one ships with, as its vendor shows it.
• Lighthouse is a lab measurement. The same page can vary by a few points between runs. Trends over many runs, which every theme's page shows, mean more than one number.
• The platform is in the score. A Shopify or BigCommerce page carries the platform's own scripts; a static Astro site carries almost none. Compare within a platform first.
• Nothing here is paid for. Vendors cannot buy a position, and no theme is tested differently because of who made it.

Corrections and requests

If a theme is missing, its demo address is wrong, or a page is being excluded that should not be, write to [email protected] with the theme's marketplace link. Themestested is built and run by Whirlwind eCommerce.

This page was generated on 2026-09-14 from the same data as the rankings.