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For eco-conscious businesses looking to minimise the environmental impact of their websites, the first step is to know how much carbon it currently generates.

In this article, we take a look at the statistics around digital emissions, explore how website carbon emissions are calculated, and then offer some suggestions for reducing the carbon footprint of your own business website…

Website carbon emission statistics

The carbon emissions generated by websites, and the internet more generally, have been increasing since the internet was born. The number of people with access to the internet is growing globally, and as data gets faster and cheaper, we are all consuming more, and we’re consuming bigger. Bigger files, longer videos, more streaming… even ordinary business websites are becoming more data intensive.

So what impact does this all have on the environment? Here are a few sobering statistics about the emissions generated by digital technologies…

  • By 2025, the IT industry is expected to account for 20% of all global electricity being used.
  • Digital technologies are responsible for 4% of global greenhouse gas emissions.
  • Digital technologies cause 1.7 billion tonnes of greenhouse gas emissions globally – that equates to 414kg of CO2 per internet user every year.
  • According to figures from Google, one internet search produces 0.2g of CO2.
  • The average website produces as much as 1.76g of CO2 per page view.
  • An average website with 10,000 page views per month could generate 211kg of CO2 per year, which is the same as would be absorbed by 105 trees in a year.
  • The average web page size has increased dramatically over the past 10 years, from 810kb to 2.28MB.
  • According the HTTPArchive, the average page loads in 1.9 seconds on desktop and 3.6 seconds on mobile.

While data speeds have gotten faster, page-load times have not – there are inefficiencies in web design that are having an environmental impact.

Learn more about designing websites sustainably in our article What is sustainable web design?

The problem with calculating website emissions

Calculating the carbon footprint of a website is difficult. There are so many variables in play that it’s tricky to know when and where we should begin our calculations.

Do we take into account the energy being used by the server that loads our website, for example? Should we factor in the manufacturing emissions of the server itself, given that servers get replaced every 3-4 years? What about the manufacturing and resources required to build the end-user device? Or the ongoing maintenance and upgrading of telecoms infrastructures required for the initial internet connection?

When we factor in every item, resource and action that goes into connecting our visitors with our websites, the emissions start to look, frankly, terrifying. But is factoring everything in a fair way to calculate our website emissions?

How are website carbon emissions calculated?

There are some fantastic businesses and organisations who are doing important, positive work in this area to clarify the issue and give us all a deeper understanding of our digital carbon impact.

One group of purpose-led businesses – Wholegrain Digital, Mightybytes, Medina Works, EcoPing and the Green Web Foundation – have worked together to come up with a set of open standards for estimating the carbon emissions from digital products and services.

Key to formulating these standards has been nailing down the right system boundaries to base emission calculations on – all those variables we mentioned earlier.

Define the systems too narrowly, and you get an unrealistic representation of energy use. Cast the net too wide and you have to calculate emissions from an increasing number of complex variables.

For their calculations, the group settled on system boundaries that included:

  • Consumer device use: 52% of the system
  • Network use: 14% of the system
  • Data centre use: 15% of the system
  • Hardware production: 19% of the system

Sounds fair enough, right?

The maths gets a little complicated from here, so buckle in.

Once they’d defined the ‘system’, they came up with a set of formulas for calculating the carbon footprint of a website. They used the key metric of kWh/GB, and based calculations on the global average carbon intensity of electricity of 442g per kWh.

They also factored in the impact of renewable energy being used by the hosting provider, giving that a figure of 50g of emissions per kWh. Annual end-user traffic emissions were determined to be 0.81 kWh of electricity per GB of data.

The formulas they came up with include:

  • Energy per visit (E), where E = Data transfer per visit (new visitors) in GB x 0.81 kWh/GB x 0.75 + Data transfer per visit (returning visitors) in GB x 0.81 kWh/GB x 0.25 x 0.02
  • Emissions per visit in grams of CO2 (C) where C = E x 442g/kWh

You can learn more by reading the full methodology for calculating digital emissions.

Tools for testing how much carbon your website produces

Happily for eco-conscious businesses who care about the impact of their website, there a number of brilliant online tools that do the complicated maths for you.

  • Website Carbon Calculator – This popular tool by Wholegrain Digital is a fantastic resource for helping businesses get a quick idea of the environmental impact of their website using the formula above. You simply input a web address, and you’ll get a quick report about that website’s emissions with real world comparisons that are easy to understand.
  • Digital Beacon – This gives you a detailed breakdown of your website’s carbon footprint, including CO2 generated on the first visit and a return visit, and the size of the data transfers required. It also tells you the size of key files on the page, including images, scripts, fonts and stylesheets – all of which forms a handy baseline for making improvements.
  • Ecograder – Developed by MightyBytes, this useful tool provides you with a score out of 100, broken down into categories such as user experience, accessibility and page size along with pointers on where you can make further improvements.
  • Google Lighthouse – This developer tool generates an in-depth analysis of your web page, covering everything from page-load speed to accessibility and SEO performance. As an automated tool, it provides a great basis for making improvements to your website generally, but can be particularly useful in knowing where you can speed things up to lower your emissions.

Learn more about website carbon testing in our full article Tools for calculating your website’s CO2 emissions.

What counts as a low-carbon website?

A low-carbon website is defined as one that produces less than 0.5g of CO2 per page load. When we’re designing and developing low-carbon websites at Root Web Design Studio, we typically aim for emissions further below 0.5g CO2 per page load. The page you’re looking at right now, for example, generates around only 0.03g CO2 per page load.

So a Root website is firmly in the ‘sustainable website’ category. Which is great for your business’s green credentials, but there are plenty of other business benefits to having a low-carbon website.

  • Show up higher in search engines. Google in particular rewards fast-loading websites above their slower counterparts, making it easier for you to reach your audience.
  • Provide a better user experience for your visitors. Slow-loading websites are frustrating and can even drive visitors away. If you provide a positive experience for your visitors, you’ll increase the chances of them being able to do what they came to your website to do, whether that’s find information, make an enquiry or buy something.
  • Work better on mobile phones. If your business serves customers directly, half your audience is likely to come to your website on a mobile phone. Providing a speedy page load for mobile users is essential, especially when signal can be sketchy.

Check out our examples of low-carbon web design in our WordPress website development gallery.

How can I reduce the carbon footprint of my website?

Once you know how much carbon your website generates, you can start to take action to bring those emissions down. If you’re starting from scratch with a new business website, a web designer who’s committed to sustainability will be able to design a low-carbon website from the ground up.

Here at Root Web Design Studio, as an eco-friendly web design agency, we use thoughtful back-end development, purposeful design and concise, SEO-led copywriting to minimise the environmental impact of your website – all of which is good for business, good for visitors, and better for the planet.

If you’re looking to make sustainability changes to a website that’s already up and running, here are a few things you can do to reduce the carbon impact:

  1. Reduce the number of files on each page. The more files on a page, the longer it takes to load. The longer it takes to load, the more energy uses. And the more energy it uses, the more carbon it generates. Reducing the number of files – including images, fonts, stylesheets and scripts – on a page will mean it loads faster, thereby reducing its carbon output.
  2. Reducing the size of the files. Compressing and right-sizing the files on a page will mean they load in the shortest time possible. Save images in the most effective format (photos as .jpg, graphics on transparent backgrounds as .png and icons as .svg) and run them through a compression tool like tinyPNG or SVGOMG. Text files like JavaScript and CSS files can be minified to remove unnecessary characters of code, shaving off additional kilobytes and load time.
  3. Be purposeful in your use of video. Video files are naturally much larger than static image files, so it’s important to be mindful about how and where you use them. The current trend for video content is adding massively to the size and environmental impact of websites, and it is often unnecessary. Your customers will generally be better served through conscious and concise copy that helps them do what they came to your website to do, rather than having to watch a 5-minute video to find the information they were looking for.
  4. Choose sustainable hosting. There are plenty of hosting companies out there these days that use green energy to power their data centres, server rooms and offices, and this has a knock-on effect on your website’s eco credentials. You can check whether a hosting company uses green energy by running their name through the Green Web Foundation tool.
  5. Choose a quality hosting package. When choosing your hosting company, try and find one that offers compression and caching techniques as part of the package – this will help to further reduce the load time of your website and its environmental impact. Our Sustainable web hosting guide can help you find a good provider.
  6. Use a Content Delivery Network. If your website receives regular visits from worldwide users, a CDN can help reduce the carbon impact of their visit. It does this by loading a copy of your site from a server that’s located in the same country as them, making it a much more environmentally friendly page view.

Read more about low-carbon website design in our article How do I make my website more eco-friendly?


We hope this article has given you a good understanding of how website carbon emissions are calculated, as well as some inspiration for making your own website more sustainable. We’ve spoken about how:

  • Calculating the carbon output of websites isn’t easy, but there are a number of brilliant tools out there to help businesses get a good picture of their website’s emissions.
  • There are small changes you can make to your own website, right now – compressing images, reducing the use of video and tracking scripts, minimising the number of fonts used – that will make a huge difference to the amount of carbon it generates.
  • Choosing a sustainable hosting company can reduce the carbon output and environmental impact of your website through its use of green energy and carbon-offsetting.
  • Having an eco-conscious web designer build your website will give you a beautiful-looking website that’s good for visitors, good for business, and better for the planet.

Further reading

To learn more about the digital carbon emissions, check out the following resources:

beautiful websites,
rooted in good ethics

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