Electricity
The calculations are based on technical specifications and documents issued by the USA Independent Department of energy analysis and statistics (United States Energy Information Administration (EIA). On average, energy sources emit 0.608 kg. (1.34 lbs.) of CO
2 per kWh. Every place on earth may have already different emissions as there are places as methods of clean energy, but for purposes of calculations is used the average of U.S. Calculations were made taking into account the average value of power equipment connected, in the case of the bulbs are 40, 60, 100 watts and the computer is 40, 70, 120 watts, depending of PC type.
Transportation
Cars
The vehicle emission estimates were calculated using technical documents issued by the United State Environmental Protection Agency (EPA) from U.S. According to these documents, gasoline has an emission factor of 8.78 kg. (19.4 lbs.) of CO
2 per gallon. Diesel fuel has an emission factor of 10.1 kg. (22.2 lbs.) of CO
2 per gallon.
Efficiency values were taken from the Environmental Protection Agency (EPA) from U.S., where small cars have an efficiency of 29 miles per gallon; medium trucks 26 miles per gallon, mpg and large trucks, vans and SUVs have an efficiency of 21.5 miles per gallon.
For users who are part of the Commonwealth colony, MPG calculations change, and t in such locations a special measure is made using gallons, called Imperial Gallons. To convert those gallons to gallons used in most of the world, need to take this figure and multiply by a factor of 0.83. (Source: Digital Dutch Calculator).
Aircraft
Aircraft emissions vary depending on the flight path. CO
2 emissions per mile for short flights is 0.29 kg per passenger, for medium flights 0.20 kg, while for longer trips, emissions are 0.18 kg per passenger. (Source: GHG Protocol Initiative and the World Resources Institute).
Flight calculations are performed by estimating the miles of flight hours and the average speed of existing aircraft types where the light aircrafts have an average speed of 187 mph, 435 mph standard commercial aircrafts, transAtlantic aircrafts or international flights of 591 mph. (source : manufacturer)
Trains
Emissions from bus trips depend on the distance traveled. Local buses generate 0.30 kg (0.66 lbs.) of CO
2 per passenger per mile and for long trips generate 0.08 kg (0.18 lbs.) per passenger per mile (WRI Source: Employee commuting spreadsheet).
The calculations are made taking into account travel times and average speeds, depending on the type of travel. For local travel within the city is established an average speed of 55 mph. Domestic travel with a speed of 125 mph and international travel have an approximate speed of 185 mph.
Bus
Emissions from bus trips depend on the distance traveled. Local buses generate 0.30 kg (0.66 lbs.) of CO
2 per passenger per mile and for long trips generate 0.08 kg (0.18 lbs.) per passenger per mile (WRI Source: Employee commuting spreadsheet).
The calculations are made taking into account travel times and average speeds, depending on the type of travel. For local travel within the city is established an average speed of 35 mph. Domestic travel with a speed of 50 mph and international travel with a speed of 65 mph.

1 kilogram = 2.20462262 Pounds

1 pound = 0.45359237 Kilograms

1 mile = 1.609344 Kilometers

1 kilometer = 0.621371192 Miles

1 Imperial Gallon = 4.546 Liters

1 Liter = 0.21998 Imperial Gallons

1 Gallon = 3.78528 Liters

1 Liter = 0.26418 Gallons

1 imperial gallon = 1.20095 Gallons

1 gallon = 0.832674 Imperial Gallon

1 kilowatt hour = 3.413 British Thermal Units (BTUs)

1 metric ton = 2,204.6 Pounds

1 Pound = 0.00045 Metric Ton

1 small ton = 2,000 Small Pounds

1 small ton = 0.90719 Metric Tons
CO2 fixation by trees
The value of CO
2 fixation by trees used in calculators is 30.07 tons of CO
2 per hectarea per year. Taking into account that the density of trees planted in Hacienda La Paz, is 1333 per hectare, fixing the value of CO
2 for each tree is 22.6 kg of CO
2 per year.
(Source: Undergraduate Thesis Universidad Nacional de Colombia  Victor Hugo Gutierrez Velez "Technical and Economic Feasibility of the Use of Pinus patula plantations as sinks for CO2)