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Free tool 02 · XcodeFix SEO Lab · No sign-up

Website Carbon Calculator CO₂ per page view, measured

Every page view uses electricity in data centres, networks and the visitor’s device. Enter a URL and we’ll weigh the page and everything it loads, check for green hosting, follow every gram of CO₂ — and show you how to cut it.
  • SWD v4emissions model
  • A+–Fcarbon rating
  • 5savings levers
  • ~30 sper test
Try:
Your report will appear here. You’ll get an A+ to F carbon label, the journey of every gram from data centre to device, a page-weight breakdown, third-party audit, optimisation opportunities and a what-if savings plan.
How to use it

Weigh any page in three steps

  1. 1

    Enter a URL

    Paste any public web page — your home page, a heavy landing page or a competitor’s — and press Calculate.
  2. 2

    We weigh it

    We download the page and the CSS, JavaScript, fonts and images it loads up front, check your host with The Green Web Foundation and apply the SWD v4 model.
  3. 3

    Get your plan

    See your grade, where the CO₂ goes and which files weigh most. Flip the what-if switches to see how far each fix moves your grade.
Methodology

How we calculate a page’s carbon footprint

Transparent, published methods — the same family of calculations used by CO2.js and websitecarbon.com.
01

1. Weigh the page

We add up the bytes transferred for the HTML and every stylesheet, script, font and image the page requests up front — compressed, exactly as they travel over the network.
02

2. Bytes → energy

SWD v4 assigns energy per gigabyte to data centres (0.055 kWh), networks (0.059) and user devices (0.080), plus the energy embodied in building that hardware (0.012, 0.013 and 0.081).
03

3. Energy → carbon

Energy is converted at the global average grid intensity of 494 g CO₂e/kWh. Verified green hosting uses 50 g/kWh for the data-centre share.
04

4. Rate it

The grams per view are placed on the SWD rating scale from A+ (0.040 g or less) to F (more than 0.359 g).
05

5. Compare it

We estimate how your page weight compares with the web as a whole, using the HTTP Archive page-weight distribution (median around 2.3 MB).
06

6. Know the limits

Images that load lazily as you scroll and files fetched later by scripts are not counted, and repeat-visit caching is not modelled, so results reflect a typical first view.
Reduce your footprint

Six ways to make a website lighter (and faster)

Most of a page’s weight comes from a handful of files. These fixes usually deliver the biggest cut in both CO₂ and load time.
01

Serve modern image formats

WebP and AVIF images are typically 25–50% smaller than JPEG and PNG at the same quality. Resize images to the size they are displayed at.
02

Lazy-load below the fold

Add loading="lazy" to images and iframes that are not visible on first load so they only download when someone scrolls to them.
03

Tame third-party embeds

Video players, chat widgets and tag managers can outweigh your own content. Use click-to-load facades for YouTube and maps, and remove tags you no longer use.
04

Compress and cache

Serve HTML, CSS and JavaScript with Brotli or gzip, and give static files a long cache lifetime so returning visitors download almost nothing.
05

Use fewer font files

Every weight and style is a separate download. Limit families and weights, use WOFF2 and consider a single variable font or the system font stack.
06

Choose a green host

Hosting on renewable energy lowers the data-centre share of every page view. Ask your host for evidence or pick one listed by The Green Web Foundation.
More free tools

Check the other two audiences of your page

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AI Search Readiness Grader

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Open the AI Search Readiness Grader
Free detailed SEO audit report

Make your site lighter, faster and easier to rank

Our free detailed SEO audit pinpoints the heavy files, scripts and third-party tags slowing your pages down — and the Core Web Vitals and ranking wins that come with fixing them.
Free · No obligation
Your free detailed SEO audit report
  • Technical SEO & Core Web Vitals review
  • On-page content & keyword gap analysis
  • AI search visibility in ChatGPT, Gemini & Perplexity
  • Backlink & local SEO health check
  • Prioritised fix list from an SEO specialist
Prepared by the XcodeFix SEO team · Coimbatore, India
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FAQ

Website Carbon Calculator FAQ

Still curious? Ask our SEO team through the free audit form.
How much CO₂ does a web page produce?
It depends mostly on how much data the page transfers. Under the Sustainable Web Design Model v4, a typical 2.3 MB page produces roughly 0.34 g of CO₂e per view, while a lean 0.5 MB page produces under 0.08 g. Multiply by your monthly page views to see the yearly footprint — the calculator does this for you.
What is the Sustainable Web Design model?
The Sustainable Web Design Model (version 4) estimates the energy used to load a web page across data centres, telecom networks and the visitor’s device, including the energy embodied in manufacturing that hardware. It is maintained by the Sustainable Web Design community, implemented in The Green Web Foundation’s CO2.js library and used by websitecarbon.com.
What does the A+ to F rating mean?
The rating places the CO₂ per page view on the Sustainable Web Design scale: A+ is 0.040 g or less, A up to 0.079 g, B up to 0.145 g, C up to 0.209 g, D up to 0.278 g, E up to 0.359 g, and F anything above that.
What counts as green hosting?
We check your domain with The Green Web Foundation, which keeps a public directory of hosting providers that show evidence of running on renewable energy. If your host is listed, the data-centre part of your emissions is calculated with a low-carbon intensity of 50 g CO₂e/kWh instead of the 494 g global average.
Does a lighter website help SEO?
Indirectly, yes. Fewer and smaller files mean faster loading, better Core Web Vitals and a smoother experience on slow mobile connections — all of which support rankings and conversions. The heaviest files and third-party scripts listed in your report are usually the quickest speed wins.
Why are my results different from other carbon calculators?
Tools differ in how they load a page and which model version they use. We measure the HTML and the files it requests up front, without running JavaScript, and we do not count images that load lazily as you scroll. Browser-based tools may count more files, and older calculators use earlier model versions with higher energy figures.
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