Calculator Sources and Methodology

Carbon footprint calculators are great tools to get an estimate of your emissions footprint. There are plenty of calculators available online. Keep in mind, however, that the mathematical models behind each of these calculators use different underlying assumptions and levels of sophistication, so it is not uncommon for two calculators to give you slightly different results. On this page we explain our calculation methodology, which is broken down into four sections that represent the biggest components of an individuals' carbon footprint, as well as the sources for our data.

Home Emissions

Data used to calculate this portion of our calculator is sourced from data published by the International Energy Agency (IEA). The IEA publishes annual estimations of CO2 emissions from fuel combustion in individual countries associated to various sectors. Depending on the user's country selection, we use the total per capita emissions of that country minus the transportation emissions, since these are calculated separately below. The per capita emissions are then multiplied by the number of people in the user's household to determine the total household emissions.

Food Emissions

The base data used in this section of our calculator is sourced from shrinkthatfootprint.com, who published estimates of the 'foodprint' of 5 different diet groups. Our calculator has adopted the same 5 diet groups used in the study; Meat Lover, Average, No Beef, Vegetarian, and Vegan. However, the values of the foodprints presented in the study are of American consumers. Therefore, in order to get a more representative foodprint for you, we multiply these values by the ratio of the total CO2 emissions of your selected country, to the total CO2 emissions of the USA.

Car Emissions

The car emission data was sourced from the Government of Canada's 2018 Fuel Consumption Guide. The guide provides emissions estimates (in gCO2/km) for hundreds of consumer vehicles, including cars, pickups, SUV's and vans. To simplify the calculator, we created 9 common categories of vehicles, according to the type of vehicle and engine size. We then filtered and averaged the published data from the guide to get representative estimates for each category. The average value of your selected vehicle type is multiplied by your distance driven to get your total car emissions estimate.

Flight Emissions

The data used for estimating your flight emissions is based on calculations which we made for 13 flights of varying duration. The equation and parameters used for calculating each of these flights are listed below. The results of the 13 flights were cross-plotted as flight duration VS estimated emissions, and a trendline drawn through the points. This trendline is then used to calculate your emissions based on your input flight duration, which is then multiplied by the number of passengers that you entered.

One-way Single Passenger Flight Emissions = ([3] * [4] * [6] * [7] * [8] * [9] * [10]) / ([2] * [11])  tons of CO2 per passenger

  1. Aircraft Type: Long haul flights (duration > ~3.5 hours, distance > ~3000 km) assumed a Boeing 777 aircraft, and short haul flights (duration < ~3.5 hours, distance < ~3000 km) assumed an Airbus A320.

  2. Number of Seats: The number of seats used for the Boeing 777 aircraft was 395 seats, and for the Airbus A320 aircraft was 154.

  3. Radiative Forcing Index (RFI): Radiative forcing accounts for climate impact resulting from non-CO2 emissions released by aircraft at high altitude. Radiative forcing is factored into flights emissions estimates using an Radiative Forcing Index (RFI). An RFI value of 3.0 was used for the long haul flights, and 2.7 for short haul flights.

  4. Fuel Burn: The fuel burn for the Boeing 777 assumed a value of 9.04 kg/km, and for the Airbus A320 a value of 2.79 kg/km was used.

  5. Flight Duration: Flight durations were obtained using results from greatcirclemapper.net.

  6. Flight Distance: Flight distances were also obtained using results from greatcirclemapper.net.

  7. Emissions Index: The emissions index was assumed to be 3.16 kg of CO2 per kg of fuel burned.

  8. Passenger-Freight Ratio: A ratio of 0.82 was used for long haul flights, and 0.9 for the short haul flights.

  9. Landing & Take-Off Emissions Factor: A significant portion of a total flight's emissions occur during take-off & landing (LTO), and an LTO factor of 1.25 was used.

  10. Cabin Factor: The emissions footprint of a passenger depends heavily on the cabin class flown. Four cabin classes are assumed; Economy, Premium Economy, Business, and First class, and factors of 0.82, 1.00, 2.07 and 4.79 were used respectively, using a World Bank study as a guide.

  11. Passenger Load Factor: This factor accounts for how full or empty a flight is. A passenger load factor of 0.76 was used.