Carbon dioxide emissions calculator

This carbon dioxide emission calculator will help you gain an approximate idea of how many tons of carbon dioxide some of your activities generate and how many trees it would take to offset those emissions - free to use! Webmasters - get this script for your site.

Carbon calculator usage instructions

  • Enter the appropriate figures into the quantity column - all fields are optional. If you usually work in metric, there's also a handy conversion feature below.
  • The number of tons of CO2 emissions will be displayed in the right hand column of the carbon footprint calculator.
  • At the bottom of the form, the total estimated amount of carbon dioxide emissions will be displayed as an annual and monthly figure in short tons (1 short ton = 2000 pounds).
  • Below the emissions figures will be the estimated number of trees needed to offset those emissions both annually and monthly.
  • Explanatory notes are below the carbon calculator as to how those figures were obtained.

Need to convert from metric? 
Click here for handy pop-up converter.


Total Tons of CO2 annually

Small car
(40 mpg fuel economy)

miles per month

Average/medium car
(21 mpg fuel economy)

miles per month

SUV/4 wheel drive
(15 mpg fuel economy)

miles per month

Electricity usage


Natural/propane gas 

cubic feet/month

Fuel oil heating 

gallons per month
Air Travel 

miles per month
Train Travel 

miles per month
General food & waste - how many people in your household?

no. of people


How many people in your household have meat in their diet?

no. of people

Total annual emissions

Total monthly emissions tons
No. of trees to offset
per year


No. of trees to offset
per month


Notes on CO2 emissions footprint calculator: 

The carbon footprint calculator is not designed to be 100% accurate as there are too many variables required in order to give a reliable emissions total. It is simply to give you an indication on how much carbon dioxide you generate and how many trees it would take to offset those emissions. 

Bear in mind that just about all we do in modern life produces a carbon footprint, well over and above what occurs in the natural world. For instance, the computer you are viewing this on was produced using processes that create carbon emissions.  Offsetting should be seen as a last resort; reduction in consumption is the first line of defense against global warming. 

Unlike many carbon footprint calculators available on the web, I thought I'd let people know how these figures are arrived at in my script. The calculations are based on the following:

  • Household electricity is based on a figure of 1.5 pounds of carbon emissions per kilowatt hour generated by a coal fired power station.3 Averages for USA based on Department of Energy, for Canada, the Ontario Ministry for Energy; for the UK, UK Environment Watch and for Australia, various state government environmental departments (averaged)
  • Natural gas emissions calculated on 0.12 pounds of carbon dioxide per cubic foot.5
  • Fuel oil based on 22.29 pounds CO2 emissions per gallon.5
  • Small car emissions calculated on .59 pounds emissions per passenger, per mile1
  • Medium car emissions calculations based on 1.1 pounds of carbon dioxide emissions per mile1
  • SUV/4 wheel drive carbon dioxide emissions based on 1.57 pounds per mile1
  • Air travel emissions based on Boeing 747 at average USA capacity and calculated per person1
  • Train travel calculations based on average occupancy of intercity train.1
  • Tree offset calculation is based on a tree planted in the humid tropics absorbing on average 50 pounds (22 kg) of carbon dioxide annually over 40 years2  - each tree will absorb 1 ton of CO2 over its lifetime; but as trees grow, they compete for resources and some may die or be destroyed - not all will achieve their full carbon sequestration potential. This calculator assumes that 5 trees should be planted to ensure that at least one lives to 40 years or that their combined sequestration equals 1 ton.
  • General waste is based on the USA average5 carbon dioxide emission equivalent of 1010 pounds per person per year. Please note, if your household recycles all glass, paper, plastic and cans; this aspect of the calculation could be as much as 50% less. The food aspect of the calculation is based on a vegan diet; i.e being 1.5 tons per person less than the American average of 5,600 pounds of CO2 equivalent emissions per year8.
  • Based on the average American diet generating the equivalent of 1.5 tons more carbon dioxide per year than a vegan diet.4

1 Source: Sightline Institute
2 Source: Trees for the Future 
3 Source: Various studies from around the world; averaged 
4 Source: Diet, Energy and Global Warming - Gidon Eshel and Pamela Martin. University of Chicago study, May 2006
5,6,7 Source: USA Environmental Protection Agency
8 Source: Livestock's Long Shadow - Food and Agricultural Organization Of The United Nations 2006