Several days ago I had a useful thought about food storage and preservation, and I'm finally getting around to putting it down here. I'm sure it's not revolutionary or anything, but I hadn't heard it expressly articulated anywhere else, and it's really helping me think about things, so here it is.
Fruits and vegetables constitute the bulk of what we must put away in summer for winter, at least in most households. Most of us tend just to buy our dry goods, and dairy and eggs are more of a year-round proposition, at least with modern, relatively affluent farming practices that allow for, say, winter grain feeding and lighted chicken coops. So this thought is mostly about fruits and veggies, though the same thinking could of course be applied to other stuff if it were relevant to you. (If, for example, you were dependent on your own dairy or eggs--you lucky dog you--then of course there are ways of preserving milk and eggs).
The USDA (leaving aside any doubts we might have about the general validity of their dietary guidelines, let's assume this one's reasonable enough) recommends 3-5 servings of fruits and vegetables per day. I think it's reasonable to say that a seasonal diet would look more like five (or more) servings of fruits and vegetables during the growing season, and three servings the rest of the time. Simply put, then, for every day of summer, you need to average roughly 3 servings of fruits or vegetables per person in the household going into winter storage.
Another useful way of thinking about it would be to multiply 3 by the number of household members by seven to get your weekly average. Or whatever seems appropriate. For example, our household: if I calculate Evelyn in for one adult serving per day for now, and three each for Jacob and me, then in a given summer week we need to put up 49 servings of fruits and/or vegetables.
At first, that struck me as pretty intimidating, but later, as I sliced dozens and dozens of tomatoes for drying, it didn't seem so bad. After all, a lot of preserving projects work best on the large scale anyway, and a serving is not as big as we tend to imagine it. That round of tomatoes probably accounted for nearly our week's total. A quart of apple sauce is, say, five or six servings, and last year we put up twelve quarts: 72 servings. Sauerkraut is another project where you end up with a lot pretty quickly, and for relatively little effort, and of course this sort of thing is where root cellaring really shines--think of the food value:time ratio of properly storing a pumpkin or a few pounds of carrots.
Obviously there's a lot to be said for estimating on the high side--there are going to be losses both small and large (a few nutrients destroyed by heat or time here, a squash rotted before you caught it there), and you never know when you're going to end up feeding more than the usual number of people. One of the joys of a well-stocked pantry has always been being able to feed guests without worrying. And you could just as well estimate for 4 servings per day or whatever, depending on how you prefer to eat. It's just a simple, obvious way of thinking about the question of how much is enough.