Carbon Footprint Calculator The math behind the calculations

Check our a main Carbon Footprint Page.

The calculations used in the Carbon Footprint Calculator are shown below. These are estimates and are provided to give you an idea on where you stand versus the average person as well as to give you areas where you can make improvements and have the biggest impact. We reserve the right to change, fix, alter or otherwise improve on these calculations at any time. Hopefully, this number will get more and more accurate as time goes on and we do new revisions of the calculator.

Transportation Section

Car

For figuring the amount of CO2 produced by a car, we used the following equation:

1 gallon of gas produces 20 pound of CO2

Plane

There are a number of different reports on how much CO2 is generated per person per mile by the average commercial aircraft. These numbers vary from around .39 pounds of CO2 per mile to well over 1 pound. We used 0.6 pounds of CO2 per person per mile for this calculation.

Of course, this is an average number based on the average fairly full commercial aircraft. If you are a CEO or movie/rock star who travels via private jet, the number would be 30 to 100 times this number. In this case, we suggest you take your miles traveled and multiply them by at least 50 to give you an idea of your carbon footprint.

Rail

Figuring a rail or train number is fairly difficult. We took an average CO2 usage of 0.3 pounds CO2 per mile. However, if you travel primarily on a very full electric train that gets its power from nuclear energy, then the number would be significantly less. In this case, divide your miles by 2 to 4 to get a more accurate carbon footprint number.

Bus

We used 0.25 pounds of CO2 per mile on the bus for these carbon footprint calculations. This number would be higher per mile for busses that stop often (city busses) and lower for busses over long trips.

Energy Section

The CO2 generated from your home energy is calculated in this section. You can choose your state to get a more accurate representation of the CO2 you generate by the electricity you use. This is because each state gets its electricity from different sources. Some states use primarily coal (bad), while others use more renewable energy sources or nuclear energy which generate less CO2 and allow you a smaller carbon footprint. These numbers are taken from government data.

If you select "none" for the state, then a national average for the USA is used. We don't have averages for various countries, yet, but hope to add that in a future release.

The number of people who live in your house is needed so we can divide the total CO2 generated by your house amongst each person living there.

For each of the below numbers we multiply by 12 months, multiply by the pounds of CO2 generated per kWh (kilowatt hour), and then divide by 2000 to get tons (or convert to tonnes for metric).

Electricity

This is measured in kilowatt hours (kWh). As described above, it is different depending on which state or area you live in.

Natural gas

Natural gas is also measured in kilowatt hours (kWh). Government data is also used to calculate this number.

Fuel Oil

Fuel oil is measured in gallons or litres. We may add other units if requested in a future release of the Carbon Footprint Calculator.

Recycling and Activities Section

Trash

To determine your carbon footprint from trash or waste, enter in the amount of waste you produce each month. Consider this is only your trash, not the entire house in this case. Then enter in the amount of recycling you do. These numbers will generate your carbon footprint from trash.

We use sort of an oddball formula for trash. We assume you can't recycle 100% of anything. We use a formula that says around 1 pound of trash generates around 1 pound of CO2. Then we take the recycling into account.

Cars

Here you can penalize yourself for owning a car (or more than 1). If you own 1 car with another person you can use a fraction here (e.g. 0.5 cars).

We use 1 ton of CO2 per year per 1 car owned. This allows for all the other CO2 produced by the use of a car including stuff like oil changes, the manufacture of the car, etc.

Banking

Here we try to account for use of banking services. These should get less costly over time as more people use internet banking, but they will not be free of CO2. The more services you use, the more CO2 it takes for the companies providing them.

Recreation

Recreation can generate a little CO2 or lots depending on what you are doing. We've tried to give you a few options here depending on where your activities mostly lean. Pick the one that closest fits your activities. In the future we may add more options.

Furnishings and Appliances

This is not a big hitter on CO2, but we thought we would add it just so you can keep it in mind. Reusing items or using items even after they've gone out of style can be good on the environment.

Clothing

This is not a big hitter on CO2, but we thought we would add it just so you can keep it in mind. Buying second hand clothes or wearing clothes even after they've gone out of style can be good for the environment.

Food Section

Food

Food generates CO2 in many ways including the transport of food, cooking food, raising food, etc. Food is often made with oil and other products that add to your carbon footprint. We use a formula that says consuming 1 pound of food (or .5 kg of food) per day generates around 1.5 tons of CO2 in a year.

Local Food

Food grown locally does not need to be transported and, therefore, generates a smaller carbon footprint. We reduce the total carbon footprint for food grown locally by 50%.