Why do some carbon calculators give different answers?
• The amount of CO2 quoted can vary because the calculation may be complex. For example, on a flight the CO2 emissions apportioned to you will depend on the type of aircraft, number of passengers, distance flown, air temperature, wind, fuel load etc. In practice each calculator chooses a set of sensible assumptions (which it should explain). • The price of offsetting a tonne of CO2 varies because the costs depend on the location and type of project.
