We Audited 100 UK Small Business Websites for Carbon. Here's What We Found.

Most writing about sustainable web design quotes the same handful of global statistics. We wanted to know what the picture actually looks like for the businesses we work with — the plumbers, cafés, solicitors and salons that make up most of the UK web.

So we measured it. In July 2026 we ran the same crawler that powers our free website carbon audit over 100 real UK small-business homepages and put every one through the Sustainable Web Design Model. This is what came back.

How we did it

We built the sample the way a customer would: searching for local businesses — “plumber Preston”, “florist York”, “dentist Exeter” — and taking the independent firms that appeared, skipping directories, aggregators and national chains. That gave us 100 businesses across 18 sectors and 16 towns and cities, from Exeter to Edinburgh: trades, hospitality, professional services, health, retail.

For each site we audited the homepage exactly as our public tool does. The crawler fetches the page, discovers every asset an initial visit would load — respecting lazy-loading, picking one image per srcset as a browser would, counting only the font subsets a real visitor downloads — and totals the transfer. Emissions estimates use co2.js v4 (the Sustainable Web Design Model), and hosting is checked against The Green Web Foundation’s verified directory. If anything, our method is conservative: we cap the number of assets we weigh, and we don’t execute JavaScript, so anything a script loads afterwards isn’t counted.

99 of the 100 sites audited successfully; one was unreachable. We’re not naming individual businesses — the point is the pattern, not the finger-pointing.

The headline numbers

Measure	Result
Median homepage weight	1.8 MB (46 requests)
Mean homepage weight	3.0 MB
Median emissions per view	0.24 g CO2e — a D rating
Sites rated E or F	44%
Sites rated A or A+	18%
Heaviest homepage	22.6 MB (2.8 g CO2e per view)
Lightest homepage	19 KB (0.003 g CO2e per view)

The distribution is the story. Thirteen sites came in under half a megabyte — proof that a normal local-business site can be genuinely light. But 44% of homepages transferred more than 2 MB, 23% more than 4 MB, and eight sites more than 8 MB. The heaviest page we measured emits roughly nine hundred times more CO2e per view than the lightest, and they are both, functionally, a homepage for a local firm.

Where the weight comes from

Across every byte we transferred in the study:

Asset type	Share of all bytes
Images	60.5%
Video and audio	15.7%
JavaScript	10.2%
Web fonts	9.6%
CSS	2.4%
HTML	1.6%

Images dominate everything else combined. 44 of the 99 sites shipped more than 1 MB of imagery on the homepage — almost always full-resolution photographs placed straight from a camera or stock library and scaled down in the browser. The video share is concentrated in a handful of autoplaying hero videos, which are spectacular emitters: most of the 8 MB-plus club had one.

The quiet surprise was fonts. 43 sites loaded over 200 KB of web fonts — several loaded more font data than HTML, CSS and JavaScript combined. That’s usually three or four weights of a display face doing a job a system font would do imperceptibly differently.

This is genuinely good news, because images are the easiest fix in web performance: modern formats (WebP/AVIF), correct dimensions, and lazy-loading below the fold routinely cut total page weight by half or more without changing how the site looks.

The sector league table

Medians per sector, for sectors where we audited five or more sites:

Sector	Sites	Median weight	Median g CO2e/view
Landscaping	9	4.6 MB	0.57
Estate agency	7	2.9 MB	0.42
Cafés	5	2.2 MB	0.34
Joinery	7	2.1 MB	0.26
Electrical	7	2.0 MB	0.29
Dental	7	1.8 MB	0.23
Veterinary	7	1.6 MB	0.19
Building	8	1.5 MB	0.19
Physiotherapy	5	1.4 MB	0.18
Plumbing & heating	5	1.2 MB	0.14
Accountancy	6	1.0 MB	0.14
Hair & beauty	6	1.0 MB	0.12
Legal	6	0.8 MB	0.10
Garages & MOT	8	0.7 MB	0.09

The pattern is intuitive: the more visual the trade, the heavier the site. Landscapers lead the table for exactly the reason you’d guess — galleries of full-resolution project photos. The two florists in our sample (too few for the table) had a median of 7.1 MB, the heaviest of any sector.

And at the bottom: garages. The humble MOT centre, with its dated-looking, no-nonsense site, is quietly running the most carbon-efficient web presence in British small business. There’s a lesson in that — restraint outperforms polish, and plenty of those garage sites would also win on load time against the prettier competition.

The green hosting mirage

On paper, the hosting picture looks encouraging: 63% of sites passed the verified green hosting check. Look closer and it softens. More than half of those passes were the site’s CDN — Cloudflare or Google Cloud — being detected in front of whatever actually hosts the site. Verified green infrastructure either way, but it’s an accident of using a popular CDN, not a decision anyone made.

The number we think matters more: just 26 of 99 sites — about one in four — combined green infrastructure with an efficient page (a B rating or better). Green hosting under a 6 MB homepage is a bit like putting solar panels on a house with the windows open in January. The order of operations should be: lighten the page first, then make sure what’s left is served on renewables. (Here’s how to check your host in thirty seconds.)

Honest scale, honest stakes

We’re a sustainability-minded studio, so let’s be straight about magnitude: these are small numbers per site. The median site in our sample, at a thousand visits a month, emits about 3 kg of CO2e a year from data transfer — a couple of hundred kettle boils. The heaviest would be over 30 kg. Nobody should greenwash a homepage diet into planet-saving heroism.

The stakes compound in two directions, though. There are around 5.5 million small businesses in the UK; the gap between the median site and the achievable-today lightweight version, multiplied across even a fraction of them, is real tonnage. And every one of those wasted megabytes is also wasted seconds on a phone on a patchy connection — which is where your customers actually are. The lightest sites in our study aren’t ascetic; they’re just built with care. That care shows up in speed, in search rankings, and in the electricity bill of the entire chain between your server and your customer’s hand.

See where you stand

The whole study ran on the same free tool anyone can use. Put your own site through the website carbon audit — it takes about ten seconds and gives you a weight, a per-view CO2e estimate, a hosting check and an A+ to F grade against the same bands we used here.

If your result stings, the fix list is short and boring in the best way: resize and compress your images, lose the autoplay video, subset or drop the web fonts, and check your hosting. Most sites in our sample could halve their footprint in a focused afternoon. If you’d rather someone did the afternoon for you, that’s what we do.

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Methodology in brief: 100 UK small-business homepages sampled via search across 18 sectors and 16 UK towns and cities in July 2026, excluding directories and national chains; 99 audited successfully. First-view transfer measured by the OakFox carbon audit crawler (declared assets, lazy-loading respected, no JavaScript execution — a conservative measure). Emissions estimated with co2.js v4 using the Sustainable Web Design Model; ratings follow the published SWD bands; hosting verified against The Green Web Foundation directory. The anonymised dataset is free to download and reuse under CC BY 4.0 — cite this page: per-site CSV · aggregates JSON.