Website Sustainability Audits

Beta · v0.5

The internet produces around 3.7% of global carbon emissions. That’s more than the global aviation industry. It’s more than the global hotel and hospitality sector. In fact, it’s more than any single country other than the USA and China.

That’s why we’re developing the next generation of website carbon estimation tools. It doesn’t just estimate a site’s carbon impact – it provides concrete, site-specific guidance on reducing it.

Collectively, website owners and developers could help reduce global emissions enormously. Many of the sites we test could cut their footprint by a half or more with no loss of functionality or appearance. They would actually speed up their site, stand a strong chance of positively impacting their search rankings, and make it cheaper to operate and better for end users.

Get a free Overview by completing the form below, or get in touch for a consultation or to discuss implementation.

Site-specific insights you can actually use

Our overview provides every finding used to calculate your score along with an estimate of their impact. You can pass the findings directly to your developer or speak to us about help with implementation.

Linked to industry guidelines

Your site’s structure, assets, and infrastructure are assessed against concrete recommendations from the World Wide Web Consortium’s Web Sustainability Guidelines.

The latest modelling

Emission estimates are calculated using the Green Web Foundation’s leading carbon estimation library and the latest methodology from the Sustainable Web Design Model (SWDM v4).

Free Site Sustainability Overview

Beta · v0.5 A real person checks each report before it is released. We aim to do this within two working days.

Consider adding pages that get many page views, or examples of different types of pages like blog posts, archives, and so on, or a page containing video, maps or many images.

To prevent spam and abuse of our servers, we send a link to confirm the request.

Tell us more about your site (optional – makes the estimate more accurate)

Each answer replaces an assumption, and the report highlights where figures have been used that you have provided.

Where are most of your visitors?

On average, electricity is cleaner in some countries than others, and most of a page view's energy is used on your visitors' networks and devices.

Your hosting company's website or your invoice usually says where its data centres are. We can't always tell from outside, especially for sites behind a content delivery network (CDN) such as Cloudflare.

Start typing. The list contains the hosting companies the Green Web Foundation has verified as green. If yours isn't in the list, leave this blank.

Used for yearly estimates. Leave it blank and we assume 5,000, a modest figure for a small business site.

Where to find this
  • Google Analytics 4: Reports, then Engagement, then Overview. Set the dates to last month and use "Views".
  • Plausible: set the period to "Last 30 days" and use "Total pageviews".
  • Matomo: Visitors, then Overview, "pageviews" for last month.
  • Cloudflare: only Web Analytics shows page views. The "Requests" figure elsewhere in Cloudflare counts every file and every bot, and can be hundreds of times higher than real page views.
  • Your host's control panel (AWStats, Webalizer): use "Pages", not "Hits". These tools count bots too, so treat the figure as an upper limit.

People who have recently visited your site will already have much of your site's content stored in their browser, so their page views use less data. Leave it blank and we count every view as a first visit, which is the more cautious option.

Where to find this
  • Google Analytics 4: Reports, then Retention, shows new and returning users; or add "New / established" in an Exploration. Divide returning by the total.
  • Matomo: Visitors, then Engagement, "Returning visits".
  • Plausible and Cloudflare don't show this, as they don't use cookies to recognise visitors. Leave it blank.
  • As a guide, business sites often see 20–40%; sites people come back to often, such as clubs or shops, more.

We use your email to confirm the request, to send your report, and we keep it associated with the results. See our privacy notice.

How to get your free website sustainability overview

  1. Fill in the form
  2. Confirm the request by clicking the link in the email we send you. In order to prevent spam and misuse of the tool, we won’t process the report until your email address is confirmed.
  3. Your report is generated and reviewed by a member of the team. We aim to do this within two working days.
  4. You will receive an email with a link to view your report online or download a PDF.

How do I fill in the form?

  1. Provide a single URL (website’s homepage), and up to two further URLs from the same domain/website.
  2. If you have access to analytics relating to your site, filling in the Tell us more about your site section will produce more accurate calculations.
  3. If you’d like more information from us about Heatherstack, this tool, and other website sustainability products and initiatives, check the checkbox.
  4. Click Request my free overview.

The small-but-important print:
This tool estimates the carbon use of the pages you ask us to assess. You must not use the resulting report to make false, misleading, or disingenuous claims about the actual carbon emissions of your website or any other aspect of your digital presence without making clear that the figures have been modelled, not measured.

We hope as many people use this tool as possible and that it encourages and enables website owners, boards and webmasters to work towards a reduction in their digital carbon footprints. You might even, as we have, join the Green Web Foundation’s call to put your organisation’s weight behind achieving a Fossil-free internet by 2030.