Free tool · Website Carbon Audit

How green is your website?

Enter your URL and get an instant environmental audit, covering CO₂ per visit, page weight, a verified green hosting check, and an A+ to F grade. Free, no signup, no email gate, no catch.

What the audit checks

Transfer

Page weight

Every byte your page ships has to be stored, transmitted, and rendered, and each step draws electricity. We measure how much data one visit to your homepage actually transfers, the single biggest factor in its footprint.

Carbon

CO₂ per visit

Using the Sustainable Web Design Model, the peer-reviewed standard behind most digital carbon tools, that transfer converts into an estimate of grams of CO₂e emitted per page view, and an A+ to F rating.

Hosting

Green hosting check

We check your domain against The Green Web Foundation's verified directory to see whether your site runs on renewable-powered infrastructure, or whether the greenest fix available is simply moving host.

The grades

What an A+ actually means.

Grades follow the Sustainable Web Design digital carbon ratings: grams of CO₂e per visit, banded against every page tested worldwide. The median page emits roughly 0.36 g per visit, which rates an E.

A+
≤ 0.040 g
The top 5% of pages tested worldwide. Genuinely exceptional.
A
≤ 0.079 g
Top 10%. A lean, well-built page.
B
≤ 0.145 g
Top 20%. Lighter than most of the web.
C
≤ 0.209 g
Top 30%. Middling, usually with easy wins available.
D
≤ 0.278 g
Top 40%. Heavier than it needs to be.
E
≤ 0.359 g
Around the median. Half the web does better.
F
over 0.359 g
Heavier than the median page. There is real work to do.

Why it matters

A lighter site is a better business, not just a greener one.

  1. The internet runs on electricity

    Data centres and transmission networks account for around 1–2% of global electricity use, and every page view draws on both. Your website's carbon footprint is real, recurring, and, unlike most emissions, fixable in an afternoon.

  2. Carbon and conversion are the same metric

    The changes that cut CO₂ (smaller images, less JavaScript, faster hosting) are the changes that cut load time. Faster pages bounce less, convert more, and score better on the Core Web Vitals that feed Google's rankings. There is no trade-off to weigh here.

  3. Claims are cheap. Evidence isn't

    If sustainability is part of your brand, your website is the first place anyone can check the claim. A verifiable grade and green hosting you can prove beat a leaf icon in the footer every time.

Improving your grade

Four fixes, in order of impact.

Most sites don't need a rebuild to move two grades. They need someone to do the unglamorous work below. Do it yourself with our practical guide, or ask us for a free improvement plan.

01

Compress and right-size your images

Images are the heaviest thing on most pages. Modern formats (WebP, AVIF), sensible dimensions, and lazy loading routinely cut page weight by half or more without any visible difference.

How we build lean sites →

02

Ship less JavaScript

Trackers, chat widgets, embedded fonts, and framework bloat all cost carbon on every single visit. Static-first builds strip most of it out; this page you are reading ships almost none.

Static-first development →

03

Move to verified green hosting

The same site on renewable-powered infrastructure emits meaningfully less per visit, and it is usually the easiest change on this list. We migrate sites free on every hosting plan.

Managed green hosting from £9/month →

04

Design pages that say more with less

Auto-playing video backgrounds, carousels nobody swipes, five font families. A considered design brief is a sustainability decision. Leaner pages convert better too.

Considered web design →

From the journal

Read before you brief anyone.

The thinking behind the tool: what makes a website heavy, what genuinely green hosting looks like, and how to fix both.

Frequently asked

Website carbon questions, answered.

What does the website carbon audit measure?
The audit measures three things: how much data one visit to your page transfers (page weight), an estimate of the CO₂e emitted per page view calculated with the Sustainable Web Design Model, and whether your site runs on verified green hosting according to The Green Web Foundation's directory. You get an A+ to F digital carbon rating and a comparison against the other pages tested worldwide.
How accurate is the carbon estimate?
It is a modelled estimate, not a meter reading. No carbon tool can measure your exact emissions. The Sustainable Web Design Model is the most widely used methodology in the field: it combines data transfer with published figures for data centre, network, and device energy, and global grid carbon intensity. It is accurate enough to compare sites fairly and to track whether changes you make are working.
What is a good website carbon grade?
A or A+ means your page is in the top 10% of pages tested worldwide, under roughly 0.08 grams of CO₂e per visit. The median web page emits around 0.36 grams per visit, which rates an E. Anything at C or below usually has straightforward fixes available: oversized images, unused JavaScript, or fossil-fuelled hosting.
Is this audit really free?
Yes, completely. No signup, no email gate, no trial. Run as many URLs as you like. OakFox is a sustainable web studio; if your grade is poor we would obviously love to help fix it, but the tool itself asks nothing of you.
How do I reduce my website's carbon footprint?
In rough order of impact: compress and resize images (the biggest win on most sites), remove unnecessary JavaScript and third-party scripts, use system fonts or subset web fonts, switch to verified green hosting, enable caching and a CDN, and design pages with less on them. Most sites can halve their per-view emissions with a focused day of work.
Does a greener website load faster and rank better?
Almost always. The same things that cut carbon (smaller pages, less JavaScript, efficient images) are exactly what makes a site fast, and speed feeds directly into Core Web Vitals, which Google uses as a ranking signal. Lower bounce rates and better conversion follow. Green performance and commercial performance are the same work.
How do I know if my web hosting is green?
Check your domain against The Green Web Foundation's verified directory, which is exactly what this audit does. Verified green hosts have provided evidence that their infrastructure runs on renewable energy. Be wary of hosts that only claim "carbon neutrality" through offsets; that is not the same thing as running on renewables.
Why can't the audit reach my website?
Some security firewalls and website security plugins block every automated visitor, including our crawler. When that happens the audit automatically retries the measurement through Google Lighthouse, which almost every site allows. If both routes are blocked, send us the URL and we'll run the audit by hand. An over-aggressive firewall is worth knowing about anyway.
How is this different from the Website Carbon Calculator?
Same underlying science, independent measurement. We run our own crawler against your page, estimate emissions with co2.js, the open-source implementation of the Sustainable Web Design Model maintained by The Green Web Foundation, and check your hosting against the same foundation's verified directory, all in one pass. Then we add a plain-English verdict and practical next steps. And because OakFox is a working design and development studio, the advice comes from people who fix these problems for a living.

Next step

Didn't like your grade?

Send us your URL and we will reply within 24 hours with the three changes that would move it most. Free, specific to your site, and yours to act on with or without us.

Get your free improvement plan