Its a very leading question. I know a fair bit about these things, but i dont think theres a specific answer for you.

Everyones body processes different foods in a different way.

Some calories (i.e. brown rice, pasta etc) are taken in by the body and released slowly over a period of time, and very few of those calories are actually wasted.

Other calories (Cola, chocolate etc) are taken by the body vey quickly and most of the calorific value is wasted.

The other problem you have with working it out, is that the machines in the gym are giving an estimate based on a typical body type etc.

Someone who is fat and not very active will burn approx 7 cals per hour by sitting still doing nothing. An active muscular person will burn more than double that by sitting exactly the same.

Also (not anything to do with te question) but calorie counting is a really crap way of watching weight. As calories on there own contribute very little to a persons weight.

So, in summation, I dont know the answer but its a very interesting question.