Articles > Eco-led, Websites
How sustainable is your website? Measuring your digital carbon footprint
Many businesses think about their environmental impact in the physical world
Maybe you’ve taken steps to reduce waste, improve energy efficiency, or make more sustainable purchasing decisions. But few businesses stop to consider the environmental impact of their digital assets.
Your website is active 24 hours a day, seven days a week. Every page, image, video, animation, plugin, and script requires resources to load and display.
The internet can feel invisible, but the infrastructure behind it is very real.
Data centres, networks and devices all require electricity.
The larger and more resource-heavy your website becomes, the more energy is required every time someone visits it.
For businesses that care about doing the right thing, understanding your website’s environmental impact is another way to align your actions with your values.
A carbon footprint is the total amount of greenhouse gases, primarily carbon dioxide (CO₂), generated by an activity, product, service, person, or organisation.
For example:
- Driving a car creates a carbon footprint because fuel is burned.
- Manufacturing a product creates a carbon footprint because energy and resources are used.
- Running a website creates a carbon footprint because servers, networks, and devices consume electricity.
How website carbon calculators work
Several tools attempt to estimate the carbon footprint of a webpage.
One of the most widely used carbon calculators is Website Carbon Calculator.
The tool analyses factors such as:
- The size of the webpage
- The amount of data transferred
- Hosting efficiency
- Estimated energy consumption
- Estimated carbon emissions per page view
It’s important to understand that these are estimates rather than exact measurements. Just like calculating the fuel efficiency of a car journey, there are variables involved. However, these tools provide a useful benchmark that helps compare websites and identify opportunities for improvement.
It helps us understand whether our website is relatively efficient or unnecessarily resource-intensive.
A real-world comparison
To get a sense of how websites in the same industry perform, we tested several Auckland cleaning companies that appeared on page one of a Google search for “house cleaning Auckland”.
Using the Website Carbon Calculator, we found:
| Website | Rating |
| Company A | B |
| Company B | B |
| Company C | F |
Company A’s result indicates that its homepage is cleaner than 76% of web pages globally.
Company B achieved a similar result.
Company C received an F rating, indicating the page is dirtier than 67% of web pages globally.
In many ways, these results are encouraging.
A B rating isn’t a bad outcome. It shows that many businesses are already building websites with reasonable performance and efficiency in mind.
The website we built for our client The House Cleaning Company achieved an A rating, making it cleaner than 87% of all web pages globally.
Our goal for the websites we build is always to remain in the A range wherever possible while balancing the practical needs of the business, the user experience, and the client’s goals.
Why website carbon matters from a business perspective
Environmental benefits are important, but sustainability isn’t the only reason to pay attention to website efficiency.
There are also significant business benefits.
Faster websites create better user experiences
People are impatient online. When pages take too long to load, visitors are more likely to leave before they take action. A lighter website generally loads faster, creating a smoother experience for your clients.
This can lead to:
- Lower bounce rates
- Longer time on site
- Better engagement
- More enquiries and conversions
Faster websites support search performance
Search engines want to deliver good experiences to users. Website speed is one of many factors that contribute to overall website quality.
While website speed alone won’t guarantee higher rankings, a well-optimised website removes potential barriers that can affect search performance.
Smaller websites require fewer resources
Large image files, unnecessary plugins, excessive animations, and poorly optimised code all increase the amount of data that must be transferred every time a page loads.
Reducing these elements often results in:
- Lower resource consumption
- Faster page speeds
- Reduced hosting requirements
- Lower environmental impact
The same actions often benefit both sustainability and performance.
Looking beyond carbon scores
A carbon score is useful, but it only tells part of the story. We also look at page size, loading efficiency, and overall website performance.
For example, tools such as SEOptimer’s Web Page Size Checker can help identify how much data your page is transferring.
A smaller page size often indicates a more efficient website, although context is important. A photography portfolio, for example, will naturally require more image-heavy content than a simple service-based business website.
This is why it’s helpful to view website performance from multiple angles rather than relying on a single score.
The most useful question isn’t “What score did I get?”
It’s “What opportunities exist to improve?”
What contributes most to a heavy website?
When we audit websites, the biggest contributors are usually:
Oversized images
Images are often the single largest contributor to page weight. Proper image sizing, modern formats, and compression can significantly reduce data transfer.
Too many plugins
Every plugin adds complexity. Not every plugin is problematic, but unnecessary plugins can increase processing requirements and slow performance.
Video and animation
Rich media can be effective, but it should be used intentionally. Heavy background videos and animations often create substantial increases in page weight.
Unnecessary third-party tools
Tracking scripts, chat tools, popups, social feeds, and external integrations can all contribute to a heavier website. Every addition should justify its place.
Sustainability starts with awareness
Most businesses don’t intentionally create an environmentally inefficient website. They simply haven’t considered the impact before.
The good news is that awareness is the first step.
Spend a few minutes testing your website using a carbon calculator and performance tools. See how your site compares.
You may discover that your website is already performing well. Or you may identify opportunities to improve both sustainability and user experience at the same time.
Either way, you’ll gain a better understanding of how your website is performing behind the scenes.
Final thoughts
At Two Sparrows, we believe websites should be better for your business, better for your customers, and better for the environment.
That’s why we consider sustainability throughout the design and development process.
Every improvement may seem small on its own, but collectively those decisions create websites that are faster, more efficient, easier to use, and lighter on the planet.
A sustainable website isn’t about perfection. It’s about making better decisions, one page at a time.
Curious about your website’s carbon footprint?
Try running your website through a carbon calculator and see how it performs.
If you’d like help understanding the results or identifying opportunities to improve your website’s efficiency, get in touch with the team at Two Sparrows. We’re always happy to have a nerdy conversation about websites, performance, and sustainability.
FAQs
Does even a small business website really have a measurable environmental impact?
Yes. Every website uses energy through data centres, networks, and user devices. While a single page view has a very small impact, the combined effect of thousands of page views over time can be significant.
Is an A-rated website always better than a B-rated website?
Not necessarily. Carbon ratings provide a useful benchmark, but they should be considered alongside usability, accessibility, functionality, and business goals. The best website balances all of these factors.
Does changing website hosting make a difference to carbon emissions?
It can. Some hosting providers use renewable energy or operate more energy-efficient infrastructure. Hosting is one factor that can influence a website’s overall environmental impact.
How often should I test my website’s carbon footprint?
It’s worth checking whenever you make major changes to your website, such as redesigns, new functionality, additional media, or significant content updates. Regular testing helps ensure performance doesn’t gradually decline over time.