Website Carbon Report 2026: How Heavy Are New Company Websites?
Key takeaways
- A new company's homepage weighs 1.62 MB in the middle, with half of all pages between 0.59 MB and 3.47 MB.
- That is about 0.23 g of CO2 per view. At 10,000 page views a month it adds up to roughly 28 kg a year.
- The spread is huge. One page in five weighs under 0.5 MB, one in five over 4 MB. The heaviest page we measured was over 28 MB.
- Platform is the biggest lever. Code-built sites had a median of 0.47 MB, builders 2.32 MB, shops 3.59 MB.
- Heavy also means slow. Builder sites took 7.5 s to show their main content on a phone, code-built sites 3.6 s.
- A quarter or more of most pages is waste: unused JavaScript and CSS, oversized images, missing compression.
How heavy are new company websites?
Page weight is everything a browser downloads for one full load of the homepage: HTML, styles, scripts, fonts and images. It is the one thing about a website's footprint you can measure from the outside, and it drives both loading time and the energy the page needs on its way to the visitor.
There is no "normal" page. The pages spread almost evenly from very light to very heavy, which tells you the weight is a choice someone made (or didn't), not a law of nature.
Which platforms are heaviest?
We sorted every page by the system it runs on (see the companion study on new company websites for how we detected it) and took the median of each group.
| Group | Sites | Median weight | CO2 per view | Mobile score | Largest paint |
|---|---|---|---|---|---|
| Code frameworks (Next.js, Astro, Nuxt) | 18 | 0.47 MB | 0.07 g | 84 | 3.6 s |
| No recognisable system | 48 | 0.80 MB | 0.12 g | 86 | 3.2 s |
| WordPress and other CMS | 82 | 1.65 MB | 0.24 g | 69 | 5.8 s |
| Website builders (Wix, Jimdo, …) | 30 | 2.32 MB | 0.34 g | 66 | 7.5 s |
| Online shops | 11 | 3.59 MB | 0.52 g | 65 | 6.5 s |
AI site builders are not shown as a group: with 5 measured sites there are too few for a reliable median. Mobile score is Google Lighthouse performance (0 to 100); "largest paint" is the time until the main content is visible on a simulated phone.
Two things stand out. Website builders ship a lot of code they need for their editor and features, whether a page uses them or not; Wix pages had a median of 2.37 MB. Shops carry product images and shop scripts on the homepage. Code-built sites, in contrast, only ship what was written for them. WordPress sits in the middle at 1.64 MB, with a wide range that depends mostly on the theme and the page builder.
How much of it is waste?
Lighthouse lists the bytes a page could drop without losing anything: JavaScript and CSS that are loaded but never used, images larger or in an older format than needed, and text sent without compression. In the median page that is 28% of the weight. In other words, more than a quarter of what a typical new company website sends could simply not be sent.
What it means in CO2
We convert page weight into emissions with the Sustainable Web Design Model (version 4): about 0.3 kWh per gigabyte transferred across data centre, network and device, at a global average of 494 g of CO2 per kWh. Those are model values, not meter readings, so read the results as orders of magnitude.
- Per view: 0.23 g for the median page, 0.07 g for a typical code-built page, 0.34 g for a typical builder page.
- Per year at 10,000 views a month: about 28 kg for the median page, compared with about 8 kg for a light one and 40 kg for a typical builder page.
For one small company that is modest. The point is the multiplier: every page view of a heavy page costs the same energy again, and the visitor on a phone pays for it in waiting time. Our free website carbon check runs the same measurement on any address, and our guide on how green your website is explains the model in more detail.
How to make a page lighter
- Images first. Use WebP or AVIF and serve them no larger than they are shown. This is usually the biggest single saving.
- Drop what you don't use. Sliders, animation libraries, chat widgets and tracking scripts each add weight on every page.
- Host your fonts yourself and load only the weights you need.
- Choose the platform with the weight in mind. A site that is built as clean code only ships what it needs, while an editor-heavy builder ships its machinery to every visitor.
How heavy is your site?
Run the same measurement on your own homepage: page weight, CO2 per view and what could be dropped. Free, no account.
Check my website ↗How we measured
- Which sites: the 203 websites we could verify for companies newly registered in Hesse, North Rhine-Westphalia and Rhineland-Palatinate between January and September 2026 (method in the companion study). 196 homepages could be measured; the rest blocked or failed the test.
- How: one Google PageSpeed Insights run per homepage (mobile, Lighthouse), the same measurement our carbon check uses. Page weight is Lighthouse's total byte weight; waste is the sum of its savings for unused JavaScript and CSS, image delivery and text compression. Details on the tool are in the PageSpeed Insights documentation.
- When: 20 October 2026, one run per site. A single run varies by a few percent.
- Limits: homepages only (other pages can be lighter or heavier); a regional sample of new companies, not all German websites; CO2 values follow a model with a global grid average and no green-hosting adjustment.
- Data protection: we publish only aggregated figures, no list of companies or websites.