How We Calculate Carbon Output
The Carbon Calculator is designed to provide a general picture of the differences of carbon output between different modes of transportation. It does not, however, produce scientifically accurate calculations.
Driving:
We calculate how many pounds of carbon dioxide (CO2) you emit when traveling by car with the following formula:
(Number of miles traveled / The car’s miles per gallon fuel efficiency) x (Pounds of CO2 emitted while burning one gallon of gasoline)
Car Pooling:
((Number of miles traveled / The car’s miles per gallon fuel efficiency) x (Pounds of CO2 emitted while burning one gallon of gasoline)) / Number of passengers in the car
Average compact car’s miles per gallon (MPG) Fuel Efficiency: 31.7MPG
Average midsize car’s miles per gallon (MPG) Fuel Efficiency: 28.6MPG
Average large car’s miles per gallon (MPG) Fuel Efficiency: 25.8MPG
CO2 emitted while burning one gallon of gasoline = 19.4lbs/gallon of gasoline
Riding the Bus
We calculate how many pounds of CO2 you emit when traveling by bus with the following formula:
[(Number of miles traveled / The bus’s miles per gallon fuel efficiency) x (Pounds of CO2 emitted while burning one gallon of gasoline)] / Average number of bus passengers at any given time
Average bus’s miles per gallon (MPG) Fuel Efficiency: 10.0MPG
Average number of bus passengers at any given time: 10
All Modes of Transportation
A human also emits carbon dioxide while exhaling, which we add to each mode of transportation.
Pounds of CO2 emitted per day = 2.3lbs = .0016lbs per minute
Sources:
Car’s miles per gallon fuel efficiency: http://www.nhtsa.gov/cars/rules/cafe/overview.htm
CO2 emitted while burning one gallon of gasoline http://www.epa.gov/otaq/climate/420f05001.htm
Bus’s miles per gallon fuel efficiency: gobrt.org/BTI_BRT_CO2_Journal_2006.pdf
Average number of bus passengers at any given time: gobrt.org/BTI_BRT_CO2_Journal_2006.pdf
Pounds of CO2 emitted per day by humans: http://www.epa.gov/climatechange/fq/emissions.html#q7
Helpful Links:
Environmental Protection Agency: http://epa.gov/
The Bus Rapid Transit Policy Center: http://gobrt.org/
National Highway Traffic Safety Administration: http://nhtsa.org/