At the time of this article’s revision, a standard box of Kellogg’s Pop Tarts [8 strawberry-flavored pastries x 52 grams each = 416 grams net weight] costs more or less the same as a pound of tomatoes [1 pound ~4 tomatoes ~453 grams net weight].

Dollar-for-gram, there doesn’t seem to be much difference: assuming that the Pop Tarts and the pound of tomatoes each cost $2.00 [*1], a dollar worth of tomatoes weighs about 9% more than a dollar worth of pastries.

In simpler terms, with one dollar, you can buy slightly more tomatoes than you can buy Pop Tarts. Using this back-of-the-napkin calculation, it seems as though tomatoes have a slight edge over the alternative.

But that’s not the best way to compare the two. After all, prices in the real world are hardly decided based on weight. Perceived utility (or lack thereof) is in fact superior to weight when determining the price of a good or service. For example, you’d expect an ounce of gold to cost significantly more than an ounce of cookies — at least in today’s economy.

Thankfully, we have one way of measuring food’s utility [*2]: the (dreaded) calorie (kcal).

Calculating dollar-for-calorie paints a different picture: a dollar worth of Pop Tarts yields 840 kcals. A dollar worth of tomatoes yields roughly 41 kcals. That’s a 21x difference. Let that sink in for a moment.