How Much CO₂ Does a Website Produce? What 100 UK Audits Say Is Normal
The average UK small-business homepage emits about 0.24 g of CO₂e per view - around 29 kg a year at modest traffic. Real figures from our 100-site audit: what's normal, what's good, and what changes the number.
- Published
- Topic
- Sustainability
- Written by
- OakFox
The honest answer to “how much CO₂ does a website produce?” is it depends on two numbers - how heavy each page view is, and how many views you get. But “it depends” is a cop-out without data, so here are the actual figures from our July 2026 audit of 100 UK small-business homepages, measured with the same Sustainable Web Design Model used by most carbon tools.
Per page view: the honest range
- The median UK small-business homepage: 0.24 g of CO₂e per view - a D on the A+ to F scale, transferring 1.8 MB of data.
- The global median page is around 0.36 g (an E). Half the web does better, half worse.
- A well-built page: under 0.08 g (an A) - and under 0.04 g is A+ territory, the top 5% worldwide. Eighteen of our 99 sites managed it, so this is not an elite standard.
- The extremes in one national sample: 0.003 g to 2.8 g per view. The heaviest homepage emitted nearly a thousand times more than the lightest, per visit, for the same job - being a small business’s front door.
Per year: multiply by your traffic
Grams per view only mean something once traffic is applied. Using the study’s median (0.24 g):
| Monthly views | CO₂e per year (median page) | CO₂e per year (heavy page, 1 g/view) |
|---|---|---|
| 1,000 | ~3 kg | ~12 kg |
| 10,000 | ~29 kg | ~120 kg |
| 100,000 | ~290 kg | ~1.2 tonnes |
For scale: 29 kg is roughly 65 miles in a petrol car; 1.2 tonnes is in the territory of a transatlantic flight seat. A single popular page on a heavy site can quietly out-emit a business’s entire paper use - and unlike most footprint lines, this one is invisible until someone measures it.
Two things follow from the table. First, most small-business websites are a minor line in the company footprint - worth fixing, not worth panicking over. Second, the ratio is the scandal: the heavy column is the same business reaching the same customers, just with an unconsidered web page. This is the cheapest emissions reduction most companies will ever find, because the fix also makes the site faster.
What actually drives the number
From the study’s byte-by-byte breakdown of everything those 100 pages transferred:
- Images: 60.5% of all bytes. Not video, not JavaScript - photography, uploaded at camera size. 44 of 99 sites shipped over 1 MB of images on the homepage alone.
- Video and media: 16% - mostly autoplaying backgrounds nobody asked for.
- JavaScript: 10% - the villain of most performance writing turns out to be a supporting actor on small-business sites.
- Fonts: 10% - a quiet one; 43 sites shipped over 200 KB of web fonts, most of which never render a visible character.
- Hosting doesn’t change the bytes but changes the emissions per byte: verified renewable infrastructure meaningfully cuts the per-view figure - though not by enough to rescue a heavy page.
Measure yours in thirty seconds
Run your homepage through our free carbon audit - no signup, no email gate. You’ll get your page’s transfer weight, grams per view, an A+ to F rating against the same scale used above, and a verified green-hosting check. If the grade disappoints, remember the shape of the data: it’s almost certainly the images, it’s fixable in about a day, and the same work moves your Core Web Vitals - which is the rare sustainability fix that pays for itself twice. And once you’ve measured, date the result and re-test after any redesign - a carbon figure describes the page on the day it was measured, nothing more.