Email Carbon Footprint vs. Paper Letter by Mail (And the True Price of SPAM)

Woman holding a phone and looking at a laptop with a confused look on her face with dark green footprint shapes situated around her head that have inbox mail icons on them illustrating an email carbon footprint.

What’s the email carbon footprint vs paper letter by mail? How much greenhouse gas is produced in the email carbon footprint of one message? Is it more than a paper letter?

What’s the true price of spam emails? Are they more than just an annoying danger?

Admittedly, a single electronic mail communication emits not much more than a tiny puff of emissions, but when multiplied by trillions of emails worldwide, the carbon footprint of the email becomes extremely significant.

Your tech habits impact the environment…probably more than you realize.

Calculate Your Email Carbon Footprint

While most people understand that it takes a lot more energy to send a paper letter by truck (or by air or sea), it’s easy to overlook the fact that emails have an energy footprint too.

And the fact remains that when energy is used, carbon emissions are generated. Any energy…including the energy used to send an email.

Here’s the Breakdown:

When measuring the difference between an email carbon footprint vs a paper letter by mail, a standard letter size envelop can generate about 20-25 grams of emissions.

But, a standard text email generates about 4 grams of carbon emissions.

Obviously, when the standard mail is larger than a single letter, the emissions increase.

Related Reading: Find the emissions of shipping a calculate the carbon offset, shipping cost.

An email with an image attachment jumps to a whopping 50 grams. (A regular document attachment makes it about 20 grams)

The average office worker sends approximately 10,000 emails a year! (9,000-15,000 according to 2022 studies)

Email Carbon Footprint Equivalency (Approximate Amounts)
102 Emails Sent Driving One Mile in Your Car
9 Emails with an Image Driving One Mile in Your car
One year of emails 551 pounds of carbon emissions (with attachments)
One year of Emails 62 Hamburgers
One year of Emails 3048 plastic water bottles
One year of emails 138 clothes dryer cycles
One year of emails Flying 10 miles in an airplane

What Is an Email Carbon Footprint?

The carbon footprint of an email is the amount of greenhouse gas equivalent (CO2e) produced directly and indirectly when sending an electronic message.

The exact amount of the CO2 produced by sending an email includes many variables, including the energy it takes to move the email across the Internet, process it, view it, store it, reread it and delete it.

This is executed by computers, servers, and routers worldwide that operate with varying levels of energy efficiency.

An email footprint also includes the manufacturing of the equipment used to make the email system possible.

How Is the Carbon Footprint of Email Calculated?

An ordinary text email you click on, open, forward, or reply to, emits 4 grams of CO2

If that email has an attachment that measures 1 MB, the emissions go up to 19 grams, and if that attachment is then forwarded or filed, the footprint for that one email could be as high as 50 grams.

Different emails emit different levels of greenhouse gas. For example, a spam email blocked by a filter generates only 0.3 g.1

Every email has a footprint that reflects its size and the number of times it moved around.

Energy Use and Consumption

The footprint also reflects the energy used to send the email. Large data centers and colocation facilities store emails, with all their attachments and photos.

In 2014, data centers in the U.S. consumed an estimated 70 billion kWh or about 1.8% of U.S. electricity consumption.3

Computer cable lines in rows, hooked into the back of a router or machine.

(Image: Jordan Harrison9)

These tech locations require massive amounts of electricity because of the number of servers that generate heat, and which need to be cooled to be kept running.

The climate control air conditioning systems vary widely in their source of energy and efficiency. Some electricity is generated by coal-fired power plants, while others employ renewable energy like hydro, wind, solar, or nuclear.

This contributes to the carbon footprint of the email traveling through that data center.

Email Carbon Footprint Facts and Figures

Should users be worried about the carbon footprint of a few emails?

  • According to accepted statistics, the number of emails sent and received worldwide each day is about 205 billion.
  • This number grew at an average annual rate of 3 percent and reached 246 billion by the end of 2019.
  • This means that almost 2.4 million emails are sent every second and some 74 trillion emails are sent per year.1

If it’s estimated that all emails emit the lowest amount of greenhouse gas (0.3 g CO2 each), the total worldwide CO2
generated by emails would be 22 million metric tons of CO2
per year.

That’s the equivalent produced by five million cars!

If all emails emit the highest estimate (50 g of CO2 per email), roughly 4 billion metric tons of CO2 would be generated each year by emails sent around the world.

That’s the same number of emissions produced by 890 million cars.

The true estimate lies somewhere in between.

What is not in doubt is that even though one email may produce an insignificant amount of CO2, when trillions of those tiny footprints are measured at a global scale, the footprint becomes substantial.

France has already noticed this and has recently released a list of suggestions to ‘avoid sending numerous emails with attachments’ during peak demands for electricity.4

As human dependence on email and other aspects of the digital economy becomes more extensive, increased awareness of the energy required must be part of the solution.

Does Email Have a Carbon Footprint?

Every action impacts the environment, and emails are no different. Most emails, including spam, unread ones, and those we forget to delete are generally stored in the cloud.

Cloud storage requires extensive amounts of electricity, which is mostly still generated by fossil fuels.4 This means that while emails no longer contribute to paper pollution, they still contribute to carbon emissions.

The average American has around 500 unread, most likely junk, emails. If each email contributes 0.3 grams of CO2 based on carbon emissions,6 that’s 150 grams per U.S. citizen.

How Does Energy Contribute to the Carbon Footprint of Email?

Email is part of a lesser-known form of pollution: digital pollution.

It’s easy to think that the virtual world doesn’t play a part in the problems facing the planet, but although the impact the internet and the digital world have on the environment may seem distant, it’s very real.

The corner of a computer laptop screen with gmail pulled up, showing an inbox with over 150 emails and many of the emails shows look like spam.

(Image: Justin Morgan10)

The internet is based on physical infrastructure—a massive network of cables, data centers, and servers that are the foundation of internet functionality.

All that hardware has to be manufactured. And the production requires energy (mostly electricity) and produces waste.

A recent study in the UK concluded that more than 64 million unnecessary emails are sent every day.5

If everyone sent one fewer “thank you” email a day – it would save more than 16,433 tons of carbon dioxide a year.

That is the equivalent of taking 3,334 diesel cars off the road. The total impact is up to 23,475 tons of CO2 a year.

How to Calculate the Carbon Footprint of Email

Measuring the number of emissions generated by one email requires adding up lots of information about hardware, colocation centers, and electricity use.

Chart that shows the email carbon footprint equivalent on driving a car, hamburgers, plastic water bottles, clothes dryer cycles, and flying in an airplane.

Fortunately, these massive figures have already been calculated, and text-based emails emit about 4 grams of CO2e (carbon dioxide equivalent) for each one sent.

In fact, on average, one year of emailing emits about 136 kilograms of CO2e.

Is Emailing More Eco-Friendly than Paper Mail?

Compared to the energy and emissions generated by paper mail, email is certainly much better for the planet. Sending an email uses about 1.7% of the energy it takes to deliver a paper letter, which is a huge reduction.

Since data centers account for about 1% of electricity7 consumed worldwide in a year, the amount seems small. However, as tech giants grow and more operations are performed online, that number will increase.

And, when you consider that much of the world’s electricity is generated by burning coal (especially in China, Asia, and most of Europe and the Americas) this small percentage represents a growing problem.

What Is the Carbon Footprint of Regular Mail?

Most regular mail is letter-size documents, but packages and larger items are also included, which causes the carbon footprint of mail to vary.

Old paper envelopes with red and blue borders stacked on top of each other in a pile on top of old letters underneath.

(Image: Liam Truong11)

Up to 29 grams of CO2 can be emitted from the process of posting a standard letter, which includes indirect and direct emissions. Some indirect emissions are generated by transport and sorting of mail.

This number estimates that 90% of regular mail is business-related, but CO2 emissions can increase during certain times of the year, such as holidays and when seasonal items are shipped and advertised.

What’s the Carbon Footprint of Personal Emails?

Carbon emissions may not be considered much when hitting that send button, but emails are responsible for as much CO2 globally as seven million extra cars.

Every email sent uses electricity, as does the network connection using electricity while the email is transferred.

How Do Ecards Add to the Email Emissions Problem?

Emails with large attachments such as e-cards can produce up to 54g of CO2, due both to the electricity consumed by the computer and the servers that send the cards.

Sending e-cards does have an impact on our environment instead of being a benign, eco-friendly gesture.

Does Unsubscribing from Emails Reduce Carbon Footprint?

No one can stop Google from creating more data, but individuals can lower their environmental impact by taking charge of junk mail.

Deleting emails is the easiest way to reduce the carbon footprint on the computer.8 Unsubscribing from emails or newsletters you don’t intend to read or deleting emails once you’ve read them can help lower the eco-cost of email.

About 107 billion spam emails were sent and received a day in 2019. If every person deleted 10 of those emails, they could save 1,725,00 gigabytes of storage space and around 55.2 million kilowatts of power.2

How Do Email Footprints Compare with Other Things?

Sometimes, it’s easier to visualize the impact of the things that contribute to climate change by comparison. Here are some of the most common items:

Common Item Average CO2 Emissions Generated
Impossible Burger .75 kg CO2e
One load of laundry 3.3 kg CO2e
500 ml plastic water bottle 82.8 g co2e

The carbon footprint of the Impossible Burger is 0.75 kg CO2e and 13 times lower than a beef burger.

Processing plastic resins and transporting plastic bottles contribute greatly to a bottle’s carbon footprint. One 500-milliliter plastic bottle of water has a carbon footprint equal to 82.8 grams (about 3 ounces) of carbon dioxide.

Erasing the Carbon Footprint from Emails

There are several options available to reduce your digital footprint. These small changes can have a big impact on your personal carbon footprint as well.

  1. Reduce the size of emails by lowering the resolution, compressing images, and avoiding large HTML elements.
  2. Regularly clean and maintain mailing lists.
  3. Remove any contacts that unsubscribe, and update changed email addresses.
  4. Check emails thoroughly before sending them to ensure they contain all the necessary information, to avoid the need for a follow-up email.
  5. Link to files or information online rather than adding an attachment.
  6. Reducing the number of attachments is also a great idea to improve cyber security.

Reducing the carbon footprint of emails is a great way everyone can help reduce their carbon footprint without cost.

In addition, by partnering with one of the best carbon offset providers tree planting programs using tree planting offsets, anyone can erase their email carbon footprint completely! One carbon offset program that is available is the Earth-Friendly Web Usage carbon offset which allows you to do anything on the Internet and remove your carbon footprint.

Although the footprint generated by your digital activities is nowhere near the same as travel or diet, every little bit helps reduce the danger to the planet. Finding ways to limit and lower your email carbon footprint doesn’t have to be a burden…you may discover that having less cyber junk in your inbox will be a benefit in itself.

Frequently Asked Questions About Email Carbon Footprint

How Does Email Contribute to Carbon Footprint?

By using energy to create, send, store and access emails, a carbon footprint is generated.

Does Deleting Emails Reduce Carbon Footprint? Does Deleting Emails Save the Earth?

Yes, deleting large amounts of data can reduce the carbon footprint of emails.


Is Sending Emails Bad for the Environment? However, It Can’t Erase All the Emissions.

As opposed to sending a paper letter, an email is better, but it still has a cost to the planet.

Is It Good to Delete Emails?

Yes, getting rid of excessive data is a good idea.

Read More About Email Carbon Footprint


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2Green Matters. 2022. Do Emails Leave a Carbon Footprint? 10 March 2022. Web. <>

3Carbon Literacy. 2022. The Carbon Cost of an Email. 10 March 2022. Web. <>

4Statistic. 2022. The Carbon Footprint of Thank You Emails. 10 March 2022. Web. <>

5Eco 2 Greetings. 2022. News. The Carbon Footprint of Email vs Postal Mail. 10 March 2022. Web. <>

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7Hirsh, S. (2020, May 14). U.S. Expected to Generate More Electricity From Renewables Than Coal This Year. Green Matters. Retrieved June 15, 2022, from <>

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