What is a carbon footprint - definition

A carbon footprint is defined as:

The total amount of greenhouse gases produced to directly and indirectly support human activities, usually expressed in equivalent tons of carbon dioxide (CO2).

In other words: When you drive a car, the engine burns fuel which creates a certain amount of CO2, depending on its fuel consumption and the driving distance. (CO2 is the chemical symbol for carbon dioxide). When you heat your house with oil, gas or coal, then you also generate CO2. Even if you heat your house with electricity, the generation of the electrical power may also have emitted a certain amount of CO2. When you buy food and goods, the production of the food and goods also emitted some quantities of CO2.

Your carbon footprint is the sum of all emissions of CO2 (carbon dioxide), which were induced by your activities in a given time frame. Usually a carbon footprint is calculated for the time period of a year.

The best way is to calculate the carbon dioxide emissions based on the fuel consumption. In the next step you can add the CO2 emission to your carbon footprint. Below is a table for the most common used fuels:


  • For each (UK-) gallon of petrol fuel consumed, 10.4 kg carbon dioxide (CO2) is emitted.
  • For each (US-) gallon of gasoline fuel consumed, 8.7 kg carbon dioxide (CO2) is emitted.
  • If your car consumes 7.5 liter diesel per 100 km, then a drive of 300 km distance consumes 3 x 7.5 = 22.5 liter diesel, which adds 22.5 x 2.7 kg = 60.75 kg CO2 to your personal carbon footprint.
fuel type unit
CO2 emitted per unit
Petrol 1 gallon (UK)
10.4 kg
1 liter
2.3 kg
Gasoline  1 gallon (USA)
8.7 kg
Gasoline  1 liter
2.3 kg
Diesel 1 gallon (UK)
12.2 kg
Diesel  1 gallon (USA)
9.95 kg 
1 liter
2.7 kg
Oil (heating)
1 gallon (UK)
13.6 kg
Oil (heating)  1 gallon (USA)
11.26 kg 
Oil (heating)
1 liter 3 kg

Each of the following activities add 1 kg of CO2 to your personal carbon footprint:

  • Travel by public transportation (train or bus) a distance of 10 to 12 km (6.5 to 7 miles)
  • Drive with your car a distance of 6 km or 3.75 miles (assuming 7.3 litres petrol per 100 km or 39 mpg)
  • Fly with a plane a distance of 2.2 km or 1.375 miles.
  • Operate your computer for 32 hours (60 Watt consumption assumed)
  • Production of 5 plastic bags
  • Production of 2 plastic bottles
  • Production of 1/3 of an American cheeseburger (yes, the production of each cheeseburger emits 3.1 kg of CO2!)

To calculate the above contributions to the carbon footprint, the current UK mix for electricity and trains was taken into account.

Carbon dioxide is a so called greenhouse gas causing global warming . Other greenhouse gases which might be emitted as a result of your activities are e.g. methane and ozone. These greenhouse gases are normally also taken into account for the carbon footprint. They are converted into the amount of CO2 that would cause the same effects on global warming (this is called equivalent CO2 amount).

Few people express their carbon footprint in kg carbon rather than kg carbon dioxide. You can always convert kg carbon dioxide in kg carbon by multiplying with a factor 0.27 (1'000 kg CO2 equals 270 kg carbon). See my comment to the article about personal responsibility for global warming .

The carbon footprint is a very powerful tool to understand the impact of personal behaviour on global warming. Most people are shocked when they see the amount of CO2 their activities create! If you personally want to contribute to stop global warming, the calculation and constant monitoring of your personal carbon footprint is essential.

For registered users, there is a carbon footprint calculator on this website, which allows to store individual activities like, e.g. travelling by car, train, bus or air plane, fuel consumptions, electricity bills and so on (we call the individual contributions "carbon stamps"). You can then see the amount of CO2 created for each individual activity. You can do this either in advance and use it as a help for decisions or afterwards to continually sum up your carbon dioxide emissions. Klick here to see a sample carbon footprint with some activities.

An off-line carbon footprint and primary energy consumption calculator (Excel sheet) is already available in the download section.

There are graphs available on this site for the CO2 emissions per capita by country (average carbon footprint by country). In the medium- and long term, the carbon footprint must be reduced to less than 2'000 kg CO2 per year and per person. This is the maximum allowance for a sustainable living .



Useful information about carbon footprint

Hello, your website was very useful for my project that I'm doing about carbon footprint!

Carbon footprint: Need more info about personal actions

I was looking for changes we can
make to reduce carbon foot prints at
home and school and i couldn't find a great deal here.

What you can do to reduce your carbon footprint

Have a look at these recommendation for actions to reduce the carbon footprint.


Real Difference

To make a real difference you need to have governments change what is put into products we use everyday.

It is not only gasoline that makes a difference, try using soy or castor oil instead of petroleum, see how many products you can change and what difference it makes


its a real answer?



wow im doing a school project

wow im doing a school project and that helped me!

you are the same person who

you are the same person who wrote about your house i feel your pain and i wish you could email me
my email evabyrant09@email.com

Use alternative resources,

Use alternative resources, renewable

dont have

dont have a car

Need more info

type http://www.zerofootprintkids.com, and it will have you take test. after that it will show you your carbon footprint, and it will tell you what you can do to reduce your footprint.

need more info

I think you do need more info just saying it would do good for people!


this is very interesting


it is! ;)


be happy they even put this on here you selfish person

thank u :)

thank u :)

Personal Action for Secondary Carbon Foot Print

Well did you know that your life Style it self contributes largely to your carbon foot print? For instance, the more you by processed food, clothes, furniture etc you are contributing to the carbon foot print INDIRECTLY.

The Carbon Foot Print Comes in 2 layers;
1. Primary foot print - which monitors your carbon emission directly (through energy consumption)
2. Secondary foot print relates to your indirect carbon emissions (such as through your food preference, fashion , recycling practices and even in recreation activities)

i.e.Food Preference - Meat lovers emit more carbon than vegans as the process of preparing the meat is more than producing organic vegetables
i.e. Fashion - I f you are buying clothes and accessories to keep us with the fashion trends etc. again You are emitting more carbon
i.e Recreation - walking, cycling and swimming emit less or no carbon compared to Speed Boating

Therefore for Home and school level you can start with recycling which is the most common form. ReUSE is also a good method. then start going green by reducing the plastic bottles and polithin u purchase. then try to reduce the amount of processed food you eat and go organic.... its a process.... so try them out and see.... even planting trees to reduce the caron foot print is a great initiative.

I am confused on primary

I am confused on primary carbon footprint. What are the particular sources of primary carbon footprint??

raw material which contain C.

raw material which contain C.


We all can do something: www.petethepet.com


Shut up

Re:Carbon footprint:Need more info about personal actions

This condition is the same with me.Today's Wednesday & I need it on Friday as a project.

carbon footprint

hey i really liked your wedsite. it has tought me a lot about my carbon footprint.




this is very helpful to me and my partner when we are working on our project and i thought that the graph is very helpful fuel type unit
CO2 emitted per unit
Petrol 1 gallon (UK)
10.4 kg
1 liter
2.3 kg
Gasoline 1 gallon (USA)
8.7 kg
Gasoline 1 liter
2.3 kg
Diesel 1 gallon (UK)
12.2 kg
Diesel 1 gallon (USA)
9.95 kg
1 liter
2.7 kg
Oil (heating)
1 gallon (UK)
13.6 kg
Oil (heating) 1 gallon (USA)
11.26 kg
Oil (heating)
1 liter 3 kg


How much gas a bus use per L???


that's good for you guys to know

Web portals like

Web portals like carbonBulls.com are very useful in sharing green information on daily usage products and activities.


what kind of project are you doing because im doing one but i dont know how to do if i dont even know what is the caarbon footprint

im making a sign on carbon

im making a sign on carbon footprint!

Asking suggestion

Hi, I'm Sarah. I am doing my project which require me to write a summary on 'carbon footprint''.
What should I write besides its definition? Hope I'll get reply soon.


I am doing my Final year project " carbon footprint" in my college so pls send detail about the project and how to calculate the carbon in industy.......


I am doing my Final year project " carbon footprint" in my college so pls send detail about the project and how to calculate the carbon in industy.......my mailid madhan506@gmail.com


Me too! Please add more random facts PLEASE!

carbon food print

your website was very helpful to me to know more detail about carbon food print i m very much satisfied by this information

carbon foot print

i like this website thank, you for all the help!

carbonfoot print

hhiii ur site is nice n helpful

carbon foot print

hello, your website was very useful for my project.


Those stats were very helpful for my coursework.


Very interesting summary of

Very interesting summary of some important info.
But can you please cite your references/evidence base?
I'd love to use your figures in a project I'm working on, but I need some evidence.

Many thanks, AL

CO2 emission of fuels / evidence base


The figures given above are mostly calculated by myself and verified with several different sources. You can find some information how to calculate CO2 emissions at the following link:

responsibility for your carbon footprint

My company is developing and producing waste air treatment systems. So this type of calculations are almost my daily business.


How is this worked out?

How do you get 2.3Kg or CO2 from 1Kg (1 litre) of Petrol? How does this relate to the ratings of eco cars?
Of course you get more miles per Litre, but does 100 Litres of fuel in an eco friendly SMART Car produce the same ammount of CO2 as 100 Litres in a Porsche?
Thanks, Graham

Definition of carbon footprint for cars

Yes, 100 litres of fuel produce exactly the same amount of CO2 whether they are burnt in an eco car or in a SUV!

See here for the calculation of the emission for carbon dioxide (CO2).


I too would like to see the chemical formula for the combustion of gasolene or diesel.
I don't see how more CO2 by weight can be produced than the liquid being combusted.

Oxidation (combustion) process

Please have a look at the link provided in the reply just above your question. If you can't follow those explanations, please post your further questions there.

Its easy

Just beacuse burning 1litre of fuel doesn't create 2.3kg of carbon doesn't mean its footprint can't be greater than its actual weight.
To create 1 litre of fuel takes a process of refining more than 1 litre of oil.
You have to then use all types of energy to create the fuel which you need to burn coal and oil to create the enrgy to heat the oil and refine it
You need to ship the oil to the petrol station from the other side of the world whihc takes carbon.
And so on and so on

So yes most products if not all have a carbon footprint greater than there core carbon ingredients, hence the turn footprint and not say emissions.

Shock even the water you use in your tap and to water on your lawn has a carbon footprint!
It didn't make it all the way in to those pipes and to your house with no energy did it.

Product of 5 plastic bags = 1kg of CO2

Hello. Would it be possible to provide further citation or explanation of the following metric? Production of 5 plastic bags = 1kg of CO2. We are trying to verify the carbon impact of plastic bag usage and this would be extremely useful information. We could site provided a sound methodology. Thanks so much!

CO2 emission for plastic bags and water bottles

The following reasoning led to the above mentioned carbon dioxide (CO2) emission for plastics:

  • The production of 1 kg of polyethylene (PET or LDPE), requires the equivalent of 2 kg of oil for energy and raw material (see here). Polyethylene PE ist the most commonly used plastic for plastic bags.
  • Burning 1 kg of oil creates about 3 kg of carbon dioxide (see e.g. our offline carbon footprint calculator). In other words: Per kg of plastic, about 6 kg carbon dioxide is created during production and incineration.
  • A plastic bag has a weight in the range of about 8 g to 60 g depending on size and thickness. For the further calculation, it now depends on which weight for a plastic bag you actually use. A common plastic carrying bag in our household had a weight between 25 g and 40 g. So I took the average of 32.5 g.
  • Take the above relation between kg plastics and kg of carbon dioxide, and you get about 200 g carbon dioxide for 32.5 g of plastic, which is the equivalent of the average plastic carrying bag in our household. Or in other words: For 5 plastic bags you get 1 kg of CO2.

Of course you'll find different figures on the Internet. The main factors are the weight of the plastic bag and whether the grey energy (energy used for production) is taken into account.

There is now a separate text available about the CO2 emissions for plastic bags and plastic bottles.



Thanks for the thorough explanation. If we were to cite this information, do you have a preference of how you would like to be featured?


I liked this site soooo much and the info is great. I will definitely tell my friends about this and thanks again. :)