Introducing the Website Carbon Rating System 

The internet’s carbon footprint is on the rise, accounting for approximately 2-4% of global emissions  — equal to or greater than the entire aviation industry. Websites rely on a very physical infrastructure like servers, data centers and telecom networks that require electricity for both operation and production. 

We believe that awareness is the first step to positive change and so we’ve been exploring how we can leverage the popularity of Website Carbon to reduce website emissions.

Taking inspiration from energy efficiency ratings of household products, vehicles and buildings, we’ve decided to introduce a similar system to inspire the creators and owners of websites to strive for better environmental performance. 

What is the Website Carbon Rating System?

The Website Carbon Rating System was designed to measure and simplify the understanding of the environmental impact of web pages. It rates websites on a scale from A+ to F, making it easy to see how energy-intensive a website is. 

How does it work?

We set our benchmark for a good rating (A+ to E) as any site that falls below the global average CO2 emissions for desktop web pages. Ratings go from A+ (very efficient) to E (which is still better than global average). Any website with emissions that exceeds the global average receives an F rating.

This update makes Website Carbon more powerful by comparing all results to the global average, not just the web pages tested on Website Carbon. This change offers a wider view, helping users understand the environmental impact of websites on a global scale.

Website Carbon Rating Scale

Here’s how this rating system works:

RatingGrams CO2e per pageview
A + 0.095
F ≥ 0.847
Website Carbon Rating Scale (CO2 emissions per pageview)

* The Website Carbon Rating System is based on the Digital Carbon Rating System developed through the SWD collaboration. Visit for more details

Discover your site’s rating

After testing your web page on Website Carbon, you may initially see a cached result from before the introduction of our new rating system. Simply click the provided link to re-test your site, and you’ll then view the updated Website Carbon rating for your tested web page.

Why is this important?

We can see the effects of the changing climate all over the world, and if the energy consumption of the digital sector continues to rise at the current rate, we won’t be able to meet the net-zero targets set to avoid the worst effects of climate change. 

By rating websites, we aim to shift the efficiency of websites globally. We can all play our part in building a more sustainable internet for all. This not only benefits the environment but also leads to faster, more reliable websites.

We’re confident the new rating system will help us to keep pushing ourselves for higher standards along with the rest of the industry. However, it’s important to remember that perfection shouldn’t hinder progress. It’s more impactful to have millions of developers and designers building websites with sustainability in mind, even if they aren’t perfect, rather than just a handful striving for perfection.

Join us on this journey

We’d love for you to become a part of this journey toward a cleaner world where the internet is part of the solution, not the problem. You can test your website, discover your rating and explore optimisation tips on our blog or in Tom Greenwood’s book, Sustainable Web Design. As always, whether you require assistance, want to share your story, or explore our digital sustainability services, please don’t hesitate to contact us.

Special thanks

Our sincere thanks go out to our industry partners who have been instrumental in the success of the project. A special thanks go out to Beleaf for their innovative idea that is lighting the way to a greener web. We’re incredibly grateful for their dedication to this mission. Join us in making the web more sustainable for people and planet!


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