onarliog: 5) The calorie challenge: I'm about to receive a PhD in computer science in the coming months, but I'll be damned if I can compute the amount of calories in a single microwaveable bag of popcorn. I dare you, go read the back of a 3-pack box and try for yourself.
JMich: 1 gram of fat has 9 kcal. 1 gram of protein or hydrocarbon has 4 kcal. So it's a simple formula of (4*(protein+hydrocarbon)+9*fat).
No idea what the packaging you are talking about looks like though.
Pre-post edit:
Wikipedia lists some other ingredient categories, along with their energy densities, so the formula is slightly longer, but still quite easy. You could easily drop it in a spreadsheet and have it automatically calculate the calories.
Actually, in the US they at least need to report how many grams of what macro-nutrients are available in each serving. And separately, how many servings a box yields. Which is pretty good. This is sufficient info to calculate calories with some simple math.
Popcorn is a different story :) It usually comes in, say, 3-packs, and all they need to do is tell you the answer to "how many calories / how much macro-nutrients in a single pack of popped corn". Because, you know, that's what you eat. But alas, popcorn brands for some reason do this in a ridiculously convoluted way. A single serving is an absurd impractical fraction of a single pack, so first you take your calculator and go from a serving to the entire box, and then divide by 3 to get a single pack's worth. But it doesn't end there, because there is also some inexplicably big gap in calories between raw corn, and the popped yield from the same package, both listed on the package to further the confusion. The numbers don't even match up, and you're left to wonder if spending this much time on some frigging corn is warranted. This is a pretty well-known issue in the US, and you'll often see posts on this in nutrition blogs :)
I'll try to post a picture of an actual box later for everybody's amusement.
BTW. The health food craze has gotten so out of hand that rather than seeing non-GMO stamped on every single thing, something like this makes me happier these days.