After hitting 10 such of these calculators, not one of them came within a ton of any of the others in estimating my impact—in fact none of them could even get close to each other on what the national average even is. Something is amiss. Okay, I understand they're only supposed to be rough estimates, and granted they do use different methods for making calculations, and some go deeper into "secondary" information like food types (local or foreign; organic or industrial), total miles of airline travel instead of estimates, and so on. That's all well and good, but the range of these estimates is so extraordinarily off, from 7,000 to 28,000 pounds, with such an even distribution between them as to be pretty useless and call into question the underlying math behind it all. Why does it matter you may ask? Precisely because if we can't agree on this most basic of data from the get-go, we can't very well agree to the terms of the debate—and in the case of carbon offsets, to a solution. Depending on which of the calculators you consult, it would cost me anywhere from $120 a year up to $340 or more, assuming those calculations are anywhere near correct. It doesn't give one much confidence.