Websites emit carbon dioxide emissions (CO2). Recent data shows which retailers top the list of offenders versus those who don't.

Websites produce carbon emissions. Recent data shows which online brands and retailer carbon footprints are most detrimental to the environment.

According to KnownHost, a private web hosting company, Casetify tops the list of worst CO2 emitters. Every web page view produces 12.18 grams of CO2 emissions. Casetify sells tech accessories for products such as phone and laptop cases.

Websites emit carbon dioxide through web-hosting servers. These retrieve data from databases and deliver content to users’ browsers. Energy is often from fossil-fuel-based sources. Data centers house the web servers and networking infrastructure needed to run websites. This requires electricity to keep equipment cool. Many websites use content delivery networks (CDNs), which send content from different locations worldwide. This results in additional energy needed to keep those servers running. Hardware pieces for internet infrastructure (like routers and switches) transmit data, therefore using energy. And user devices, like smartphones and laptops, also use energy, according to KnownHost.

Casetify website tops list of carbon emitters

To put that in perspective, after over a year with 10,000+ monthly page views, Casetify produces the amount of carbon that 67 trees absorb in a year, or 3,306 kWh of energy (which can drive an electric car 21,158 kilometers), according to website carbon calculator Website Carbon. Digital Commerce 360 reached out to Casetify but did not receive a response regarding the findings.

There are more than 5.18 billion people using the internet worldwide, according to Statista. And the number of consumers shopping online continues to grow.


Casetify has a landing page on its website regarding its “key initiatives” to offset its carbon footprint. Actions include using 50% recycled materials and eco-friendly ink, 100% compostable packaging and sustainability-certified facilities. Some direct-to-consumer retail brands are among the top 10 producers of CO2 emissions per visit.

Casetify is followed by:

Williams Sonoma website produces lowest carbon emissions per website visit

Williams Sonoma produces the lowest carbon footprint with 0.01 grams of CO2 per web page visit. The retailer is followed by Pottery Barn (subsidiary of Williams Sonoma Inc. (0.01 grams), JCPenney (0.04 grams), Nordstrom Inc. (0.06 grams), Aldo (0.13 grams), and Best Buy Co. Inc. (0.13 grams).

Amazon tops list of companies producing most CO2 per month

The top 10 companies total operations producing the most CO2 per month include Inc., with 400,082,802 total grams of CO2 emitted per month. Amazon emitted 71.27 million metric tons of CO2 in 2022, down 0.4% from the previous year, according to Amazon’s annual sustainability report. The company has pledged to cancel out or offset its contribution to greenhouse gas emissions warming the Earth by 2040. Emissions are up about 40% since Amazon set this goal in 2019. That is due in part because of the surge of business in 2020 during the pandemic.


Amazon is No. 3 in Digital Commerce 360’s new 2023 Global Online Marketplaces Report. The Global Online Marketplaces database ranks the 100 largest such marketplaces by 2023 third-party GMV.

Amazon is also No. 1 in the 2022 Digital Commerce 360 Top 1000 database. The Top 1000 ranks North American web merchants by sales.

In addition to Amazon, the top 10 producing the most emissions per month are:

  • Taco Bell (107,150,137 grams)
  • Target Corp. (84,433,296 grams)
  • TripAdvisor (65,606,844 grams)
  • eBay Inc. (53,540,341 grams)
  • Walmart Inc. (45,943,738 grams)
  • Etsy Inc. (35,252,889 grams)
  • Nike Inc. (35,047,824 grams)
  • Wayfair (32,446,202 grams)
  • Lowe’s Co. Inc. (31,670,270 grams)

It was surprising to see West Elm rank sixth in the top 10 websites with the most CO2 produced per visit (3.01 grams), said Daniel Pearson, CEO, KnownHost.


Top Top five companies producing the least CO2 per month:

  • Williams Sonoma (21,517 grams)
  • Pottery Barn (37,842 grams)
  • Aldo (68,845 grams)
  • Cesar’s Way (116,421 grams)
  • Charlotte Tilbury (169,037 grams)
  • NYX Professional Makeup (169,067 grams)

“Especially, as it’s owned by Williams Sonoma Inc. and both Williams Sonoma and Pottery Barn — another Williams-Sonoma  [Inc.] retailer – are ranked joint first for the websites with the lowest CO2 produced per visit (0.01 grams),” he said.

“This can highlight differences in their sustainability practices and provide insight into their environmental performance,” Pearson said. “When retailers within the same parent company produce different CO2 emissions, it presents an opportunity for knowledge sharing and collaboration.”

KnownHost used a seed list of America’s Top 100 online stores in 2023 from software shipment tracker Aftership. KnownHost ran online stores’ websites through the Website Carbon Calculator individually. Each store’s monthly traffic levels were recorded using SaaS company Ahrefs, which is an SEO tool used to search for growing website search traffic. This was multiplied by the amount of CO2 produced per visit to determine the overall amount of CO2 produced each month. The number of trees it takes to absorb CO2 emissions was calculated using a figure from the U.S. Department of Agriculture.


How can retailers change tactics?

Once known, retailers can reassess and implement strategies to help reduce their carbon emissions, Pearson said.

“They can look at optimizing website efficiency by streamlining the website’s code and design to reduce page load time and server energy consumption,” he said.

Also, websites should compress images, use caching and minimize HTTP requests, he said. 

Retailers can search for eco-friendly web-hosting services that rely on renewable energy sources to power their servers and offer customers the option to voluntarily offset their shipping emissions by contributing to verified carbon offsetting projects, Pearson said.


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