The internet doesn’t look like it has an exhaust pipe. There’s no smoke, no engine noise — just a page appearing on a screen. But every one of those pages travels through data centres, networks and your visitor’s device, and all of that runs on electricity. Some of that electricity still comes from burning things. So yes: your website emits CO₂, quietly, on every single visit.
The good news is that the same thing that makes a site “greener” also makes it faster and cheaper to run. Carbon and money point in the same direction. Let’s unpack how.
Where the emissions actually come from
When someone opens your website, three things consume energy:
- The data centre that stores your site and sends it out.
- The network — the cables, routers and mobile towers that carry the data to your visitor.
- The visitor’s device — the phone or laptop that has to download, unpack and render everything.
The heavier your page, the more data moves across all three, and the more energy it takes. A bloated page with huge images, a dozen tracking scripts and three web fonts doesn’t just feel slow — it literally moves more bytes, which burns more power.
The numbers, in plain terms
The median web page today weighs around 2.4 MB and emits roughly 0.8 grams of CO₂ per visit, according to the widely used Sustainable Web Design model behind tools like Website Carbon.
Nought-point-eight grams sounds like nothing. But websites don’t get one visit. Multiply it:
- 10,000 visits a month → about 8 kg of CO₂ a month, roughly 96 kg a year.
- 100,000 visits a month → about 80 kg a month, close to a tonne a year.
That’s from a single average website. Now picture the whole web. Collectively, the internet’s carbon footprint is in the same ballpark as the global aviation industry. Your site is one small tap in a very large bucket — but it’s your tap, and you control it.
Why a heavy site costs you money
Carbon is the headline, but the reason this matters commercially is that weight and money are tied together. A heavy site hurts you in three places:
1. It’s slower — and slow costs sales. Every extra megabyte is time your visitor waits. People don’t wait. Bounce rates climb sharply as pages get slower, and lost visitors are lost enquiries. (We go deep on this in Site speed = sales.)
2. It costs more to serve. More bytes means more bandwidth and more compute. On a small site the hosting bill is minor, but the pattern scales — heavier sites need heavier, pricier infrastructure to stay fast.
3. It’s a missed trust signal. “Green” is no longer a fringe concern. Customers, especially in the EU, increasingly notice it — and a website that can prove it’s lightweight and low-carbon stands out in a sea of vague sustainability claims. A measured carbon badge is a differentiator most competitors don’t have.
So cutting carbon isn’t charity. It’s the same work as making your site fast, cheap to run, and more convincing.
How to measure yours
You can’t improve what you don’t measure. Two easy ways to see your number:
- Run a free carbon check with a tool like Website Carbon — paste your URL, get a grams-per-visit estimate and a rating.
- Use the meter on our homepage, which measures both speed and carbon in one go, and shows your site against a fast, green benchmark. That comparison is usually the moment the problem becomes real.
Either way, get a baseline in grams. That single number tells you whether you have a problem worth fixing.
How to cut it
Most of a page’s weight comes from a few usual suspects. In rough order of impact:
- Images. Almost always the biggest offender. Correctly sized, modern-format (WebP/AVIF), lazy-loaded images can cut page weight dramatically without any visible quality loss.
- Scripts. Every analytics tag, chat widget and marketing pixel adds weight and slows things down. Keep only what earns its place.
- Fonts. Two or three custom fonts, each in several weights, add up fast. One well-chosen font, self-hosted, is plenty.
- The platform itself. A heavy CMS with a bloated theme and ten plugins ships a lot of code the visitor never needed. A lean, static build ships only what’s used.
- Hosting. Serving from efficient, renewable-powered infrastructure lowers the carbon of every byte you do send.
None of this means an ugly, stripped-back site. It means an intentional one — where every kilobyte is a choice.
The Leavsy approach: measured, not claimed
This is the whole idea behind Leavsy. Every site I build is lightweight by default and served from low-carbon hosting (Cloudflare), so each visit emits under 0.1 g of CO₂ — around a tenth of the median. And I don’t just claim that: it’s measured, and shown as a live badge on the site.
You can see it in the demo builds — a bakery, a law firm and an electrician, each rated A+ for carbon at 100/100 performance, each roughly 10–13× lighter than the median site. Same measurement, real numbers.
If you’re curious where your current site stands, that’s exactly what a free 24-hour audit gives you: your speed and carbon today, and what a rebuild would change. And if you already know you want a fast, green site, the pricing is published in the open — no call required.
A lighter website is better for the planet in a small way, and better for your business in a very direct one. It’s rare that those two things line up so neatly. On the web, they do.