Having made a cursory survey of a few calculators, one striking difference is how they deal with Radiative Forcing (RF). This is designed to account for high altitude CO2 emissions being 'worse' than ground level emissions. As seen in the table below, calculators use factors ranging from 1 (no RF) to 3 (the amount of CO2 calculated is multiplied by three). Dividing the result of each calculator by the RF factor used, the relative standard deviation of the dataset decreases. Different RF factors therefore account for at least some of the differences between the initial answers.
| Calculator | RF factor | Initial answer | Undoing RF |
|---|---|---|---|
| atmosfair | 3 (>9 km) | 5,306 kg | 1,805 kg |
| brighterplanet | 2 | 2,931 kg | 1,466 kg |
| carbonfootprint | 1.891 | 2,500 kg | 1,322 kg |
| carbonfootprint | 1 | 1,320 kg | 1,320 kg |
| chooseclimate | 3 | 5,999 kg | 2,000 kg |
| clevel | 1.9 | 2,940 kg | 1,547 kg |
| climatecare | 1.9 | 2,710 kg | 1,426 kg |
| climatepartner | 3 | 4,156 kg | 1,385 kg |
| co2nsensus | 1 | 2,729 kg | 2,729 kg |
| flygrn | 1.9 | 2,730 kg | 1,437 kg |
| greentripper | 1 | 2,180 kg | 2,180 kg |
| greentripper | 2 | 3,990 kg | 1,995 kg |
| icao | 1 | 799 kg | 799 kg |
| myclimate | 2 | 3,000 kg | 1,500 kg |
| myclimate lufthansa/swiss | 1 | 1,200 kg | 1,200 kg |
| offsetters | 1.9 | 2,930 kg | 1,542 kg |
| omnicalculator flight-emissions | 2 | 5,400 kg | 2,700 kg |
| southpole | 1.9 | 3,266 kg | 1,719 kg |
| terrapass | 1 | 3,291 kg | 3,291 kg |
Calculators accessed 2020-02-08.