An email

Emissions for one email, from spam to a long message with an attachment. Each figure counts something different: open its details to see what.

The figures at a glance

Carbon emissions, highest first. On the scale, each line is ten times the one before.

50 g CO2e per email with attachmentAn email with a long attachment, How Bad Are Bananas? (2010)
17 g CO2 per emailA long laptop-to-laptop email (10 minutes to write, 3 to read)
4 g CO2e per emailA proper (non-spam) email, How Bad Are Bananas? (2010)
1 g CO2e per emailOne email, 1 g CO2e (OVO Energy "Think Before You Thank")
0.3 g CO2e per spam emailA spam email, How Bad Are Bananas? (2010)

An email with a long attachment, How Bad Are Bananas? (2010)

50 g CO2e per email with attachment

What's the carbon footprint of ... email?The Guardian (Mike Berners-Lee and Duncan Clark; draws on How Bad Are Bananas?), press article, 2010-10-21

Details

50g CO2e: An email with long and tiresome attachment

What one action is: One email with a long attachment
Claimed by: Independent: Mike Berners-Lee

History

2026-10-16 Added.

Cite this claim: copy the card

<blockquote cite="https://www.theguardian.com/environment/green-living-blog/2010/oct/21/carbon-footprint-email">
<p>An email with a long attachment, How Bad Are Bananas? (2010): 50 g CO2e per email with attachment.</p>
<p>What it counts: One email with a long attachment (scope: not stated).</p>
<footer>Mike Berners-Lee, <a href="https://www.theguardian.com/environment/green-living-blog/2010/oct/21/carbon-footprint-email">What&#39;s the carbon footprint of ... email?</a> (2010-10-21). Via the <a href="https://co2stats.com/kettle/email#berners-lee-email-attachment-2010">CO2Stats Kettle ledger</a>, CC BY 4.0; the figure keeps its source's attribution.</footer>
</blockquote>

A proper (non-spam) email, How Bad Are Bananas? (2010)

4 g CO2e per email

What's the carbon footprint of ... email?The Guardian (Mike Berners-Lee and Duncan Clark; draws on How Bad Are Bananas?), press article, 2010-10-21

Details

4g CO2e: A proper email

What one action is: One proper (genuine, non-spam) email
Claimed by: Independent: Mike Berners-Lee

History

2026-10-16 Added.

Cite this claim: copy the card

<blockquote cite="https://www.theguardian.com/environment/green-living-blog/2010/oct/21/carbon-footprint-email">
<p>A proper (non-spam) email, How Bad Are Bananas? (2010): 4 g CO2e per email.</p>
<p>What it counts: One proper (genuine, non-spam) email (scope: not stated).</p>
<footer>Mike Berners-Lee, <a href="https://www.theguardian.com/environment/green-living-blog/2010/oct/21/carbon-footprint-email">What&#39;s the carbon footprint of ... email?</a> (2010-10-21). Via the <a href="https://co2stats.com/kettle/email#berners-lee-proper-email-2010">CO2Stats Kettle ledger</a>, CC BY 4.0; the figure keeps its source's attribution.</footer>
</blockquote>

A spam email, How Bad Are Bananas? (2010)

0.3 g CO2e per spam email

What's the carbon footprint of ... email?The Guardian (Mike Berners-Lee and Duncan Clark; draws on How Bad Are Bananas?), press article, 2010-10-21

Details

The carbon footprint of spam: 0.3g CO2e: A spam email

What one action is: One spam email
Claimed by: Independent: Mike Berners-Lee

History

2026-10-16 Added.

Cite this claim: copy the card

<blockquote cite="https://www.theguardian.com/environment/green-living-blog/2010/oct/21/carbon-footprint-email">
<p>A spam email, How Bad Are Bananas? (2010): 0.3 g CO2e per spam email.</p>
<p>What it counts: One spam email (scope: not stated).</p>
<footer>Mike Berners-Lee, <a href="https://www.theguardian.com/environment/green-living-blog/2010/oct/21/carbon-footprint-email">What&#39;s the carbon footprint of ... email?</a> (2010-10-21). Via the <a href="https://co2stats.com/kettle/email#berners-lee-spam-email-2010">CO2Stats Kettle ledger</a>, CC BY 4.0; the figure keeps its source's attribution.</footer>
</blockquote>

One email, 1 g CO2e (OVO Energy "Think Before You Thank")

1 g CO2e per email (published as: 1g carbon = 0.000001 tonnes CO2e per email)

'Think Before You Thank': If every Brit sent one less thank you email a day, we would save 16,433 tonnes of carbon a year - the same as 81,152 flights to MadridOVO Energy (archived copy; the original page has been removed), press release, 2019-11-26

This figure is disputed: its details say how.

Details

x1 email = 1g carbon = 0.000001 tonnes CO2e per email (Source: Mike Berners-Lee)

What one action is: One email, used for unnecessary "thank you" emails in the UK
Place: UK
Method: The press release takes 1 g per email from Mike Berners-Lee and multiplies it by survey-based counts of unnecessary emails (Censuswide, 3,000 British adults) to reach 16,433 tonnes a year.
Claimed by: Company: OVO Energy (citing Mike Berners-Lee)
Paid for by: none
Dispute: BBC News (November 2020) reported that Mike Berners-Lee, whose research was used, told the Financial Times the work was based on "back-of-the-envelope" maths from 2010, and quoted Chris Preist (University of Bristol) that most of the system uses energy whether or not an email is sent, so "the carbon saved will be far far less than 1g per email." https://www.bbc.co.uk/news/technology-55002423

History

2026-10-16 Added.

Cite this claim: copy the card

<blockquote cite="https://web.archive.org/web/20220302172156/https://www.ovoenergy.com/ovo-newsroom/press-releases/2019/november/think-before-you-thank-if-every-brit-sent-one-less-thank-you-email-a-day-we-would-save-16433-tonnes-of-carbon-a-year-the-same-as-81152-flights-to-madrid">
<p>One email, 1 g CO2e (OVO Energy &#34;Think Before You Thank&#34;): 1 g CO2e per email (published as: 1g carbon = 0.000001 tonnes CO2e per email).</p>
<p>What it counts: One email, used for unnecessary &#34;thank you&#34; emails in the UK (scope: not stated).</p>
<footer>OVO Energy (citing Mike Berners-Lee), <a href="https://web.archive.org/web/20220302172156/https://www.ovoenergy.com/ovo-newsroom/press-releases/2019/november/think-before-you-thank-if-every-brit-sent-one-less-thank-you-email-a-day-we-would-save-16433-tonnes-of-carbon-a-year-the-same-as-81152-flights-to-madrid">&#39;Think Before You Thank&#39;: If every Brit sent one less thank you email a day, we would save 16,433 tonnes of carbon a year - the same as 81,152 flights to Madrid</a> (2019-11-26). Via the <a href="https://co2stats.com/kettle/email#ovo-thank-you-email-2019">CO2Stats Kettle ledger</a>, CC BY 4.0; the figure keeps its source's attribution.</footer>
</blockquote>

A long laptop-to-laptop email (10 minutes to write, 3 to read)

17 g CO2 per email

Concerned about your data use? Here is the carbon footprint of an average day of emails, WhatsApps and moreThe Guardian (Chris Stokel-Walker), press article, 2024-10-31

Details

If the editor took 10 minutes to write the email ... and it took me three minutes to read, and if it was sent from a laptop and received on one, then we have generated 17g of carbon dioxide (CO2) emissions already, according to estimates by Mike Berners-Lee, a professor at Lancaster University’s Environment Centre

What one action is: One email that takes 10 minutes to write and three minutes to read, sent from a laptop and received on one
Claimed by: Independent: Mike Berners-Lee (as reported by The Guardian)

History

2026-10-16 Added.

Cite this claim: copy the card

<blockquote cite="https://www.theguardian.com/environment/2024/oct/31/concerned-about-your-data-use-here-is-the-carbon-footprint-of-an-average-day-of-emails-whatsapps-and-more">
<p>A long laptop-to-laptop email (10 minutes to write, 3 to read): 17 g CO2 per email.</p>
<p>What it counts: One email that takes 10 minutes to write and three minutes to read, sent from a laptop and received on one (scope: not stated).</p>
<footer>Mike Berners-Lee (as reported by The Guardian), <a href="https://www.theguardian.com/environment/2024/oct/31/concerned-about-your-data-use-here-is-the-carbon-footprint-of-an-average-day-of-emails-whatsapps-and-more">Concerned about your data use? Here is the carbon footprint of an average day of emails, WhatsApps and more</a> (2024-10-31). Via the <a href="https://co2stats.com/kettle/email#berners-lee-long-email-laptop-2024">CO2Stats Kettle ledger</a>, CC BY 4.0; the figure keeps its source's attribution.</footer>
</blockquote>