Just to see if it would work, I tried out the calculators for a zero distance flight. Like ZRH-ZRH. Most wouldn’t let me do that, but some would. First I just tried ZRH-ZRH one way. Then, don't ask what it means, ZRH-ZRH return. For those calculators which allow a via, I added via ZRH... obviously this isn’t sensible, but it's a window to how the calculators work. Results in the table below.
Those calculators returning zero for all options must be calculating emissions with a multiplier to great circle distance. Atmosfair has a minimum flight distance of 50 km per leg. Choose climate adds a specific take off-climb-descent constant to the great circle distance.
What the calculator should do with this rather nonsensical input is another question.
| Calculator | One way | Return | One way via ZRH | Return via ZRH |
|---|---|---|---|---|
| atmosfair | 8 kg | 16 kg | 16 kg | 32 kg |
| brighterplanet | 209.79 kg | |||
| C-Level | 0 kg | 0 kg | ||
| Choose climate | 56 kg | 112 kg | ||
| ClimateCare | 0 kg | 0 kg | 0 kg | 0 kg |
| Greentripper | 0 kg | 0 kg | 0 kg | 0 kg |
Calculators accessed 2019-10-23