coefficient = (place / out) * coefficient_multiplier
where
place = the pigeon's result for this race
out = total number of pigeons for this race
coefficient_multiplier = 100 by default, can be changed in the advanced settings
So if your pigeon flies the first place out of 100 pigeons in that race, it will have a coefficient of (1 / 100) * 100 = 1
Apparently not every country calculates the coefficient in the same way, so I added the custom multiplier.
Just let me know if more info is needed.