The Shopping Cart Economist

Silly title, I know, but I’d like to convey that the size of the package does not correlate to the overall economic value of what’s inside the package.

Case in point, the watermelon. It’s my family’s favorite summertime fruit. It’s low in calories, has basically no fat, and it seems to do a great job keeping me hydrated. Here’s the problem though.

For years, I’ve resisted the personal-sized watermelons marketed by Dulcinea. $3.00 for a personal watermelon seemed excessive for a 3.5 pound melon when a large seedless watermelon could be had on sale for .39-.49c per pound on average - and sometimes even less!

So I bought my .39c per pound watermelon. The average large melon seems to range between 12-15 pounds, so for .39c per pound, the average cost of a large seedless watermelon is about $5.25. That’s nearly 10 more pounds than one of the personal Dulcinea watermelons. Great deal, right? Well, maybe not so great.

The next part of this is my unscientific, unproven (yet quasi-tested) musings about why that thinking might just be wrong.

When you have a 13-pound watermelon for $5.25, the average large variety watermelon is about 60% usable. The rest is rind weight you’re paying for. That means the usable portion is about 7.8 pounds. That brings the usable portion of watermelon up to .68c per pound. The Dulcinea is about 95% usable, meaning that for a 3.5# personal melon, your rind waste is about .12 of a pound. That’s roughly .88c per pound for usable melon.

Now that we’ve taken the rind out of the equation, the price difference between the two melon types on a pound per pound basis is only about .20c difference.

Let’s take this a few steps further. You now have 7.8 pounds of watermelon. Cut watermelon doesn’t last well much past a week. So unless your family can crank through it before it goes bad, it will wind up in the trash. Plus, in my experience, the larger the watermelon, the greater the tendency to have a mushy, stringy center that you wind up having to cut away and toss. The usable fruit that you toss in this process will increase the overall cost per pound.

If you’ve ever cut up a large watermelon, you’ll know how much trash the rind can generate. If you are cutting up that 13# watermelon, you’re left with about 5.2 pounds of waste. Unless you’re composting (and rinds take quite a while to break down), then you’re filling up your trash can faster after you buy a large melon and cut it up. Watermelons are over 90% water. The larger a melon is, the more resource-intensive it is to grow.

So for those interested in the real cost of food, who think about food miles and where their food is coming from, this is where the smaller melons make up the difference in the price per usable pound. A semitruck typically can lug forty-four thousand pounds of food. The larger the melons, the less of each unit will be on the truck. A large-melon truckload will likely generate more overall waste due to the rind weight.

The smaller melons will hit more people’s tables. They were less water intensive to grow, and they theoretically generate less waste. When you add in these other factors, which most people quite honestly don’t, the smaller melon truly does become the better deal with regards to the total economic value of what you’re buying.

A watermelon makes for a great example to illustrate this point. But it also holds true for things like cereal and bags of chips and caseload goods from big-box warehouse stores. The bigger packages aren’t always the better deal. Sales in your local grocery stores more often than not have better deals on a price per ounce/unit basis. What these bigger pack sizes do is provide convenience, but ultimately, as in the case with the melon, you might wind up paying more for the hidden costs and the loss associated with the waste than had you just bought the smaller, usable pack size in the first place. The perception of spending less to get more could actually cost you more in the long run.