When comparison shopping, trust the math, not your eyes

Recently, my grocery store began stocking a new, “family-size” package for a cereal that I enjoy. It caught my attention because the family-size box is a lot larger than the regular one. In fact, the family-size box looked almost double the size:

In a rush, I chose the family-size box and checked out. But when I returned home, I uncovered some thing that surprised me.

The family-size box turned out to have less than I expected. I was disappointed that it had 21 ounces compared to the regular, which had 16 ounces. That’s not that much bigger. In fact, that’s only a 30% increase. I was way off from my estimate that the family size box would have twice as much cereal. Did my eyes deceive me?

I hoped not, so I took out a ruler to do some measurements. The two boxes had the same length (7.5 in), but the family-size was a full inch wider (3 in versus 2 in) and almost a full inch taller (12 in versus 11 in). Doing the math, the family-size box was about 70% larger by volume. Well, at least I was right the box looked almost twice as big.

Now for the next logical question: what do you get with a box having 70% more space and only 30% more cereal to fill the space? You end up with a ridiculously oversized box. I was stunned at how little cereal the box contained:

I guess since companies are forced to label truthfully, they counter by deceiving customers in a subtle way like misleading packaging.

To keep myself honest, I always try to compare the cost per weight before buying a new packaging (the family size was cheaper, though not by much). Many grocery stores will even display these numbers for you next to the item’s price.

Have you seen examples of misleading packaging (not limited to food)? What is your best defense?



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  • Erik

    Yeah, I’ve seen this before, but not in the volume sense. I’ve noted how a box with only 25-33% more cereal (e.g. 21 oz. vs. 16 oz.) will be at least 50% more expensive. To add insult to injury, the grocery stores only discount the smaller sizes. It’s annoying, but as you said, if you check the unit cost each time, you won’t get fooled.

  • http://www.mindyourdecisions.com Presh

    @Erik: Wow, your example that bigger is not cheaper reminds me of my beer analysis where larger is not cheaper. I wonder if warehouse retailers like Costco and Sam’s Club do the same trick by selling big quantities at not necessarily lower prices…

  • http://littleredsuit.com Tiffany

    I love it – this happens all the time. One good case is many bulk stores (Sams, Costco, etc.) They will sell you a lot more in bigger packages, but you have to do the math to see if it’s really a good deal. Soda is a great example. You can get a 24 pack in bulk for about $7, but if you watch your local grocery store, 24 packs frequently go on sale for $5 or $6. Cereal is another one. They sell you a double family pack for $6 when you can buy an individual box (family style) for $2.50. Some things are significantly cheaper there, but others are definitely marked up.

  • naree

    so we’re paying a higher cost per unit… just to help companies double the usage of plastic and paper (aka pollute the environment)? ai’yo!

  • http://www.mawsoft.com/blog RohoMech

    So to be fair, I bet the cereal bag had a lot of settling, I doubt it was filled all the way up but still, it looks mostly empty because of that.

    Cereal boxes are really amusing though, the high-fiber cereals which appeal to adults typically have tiny boxes, but weight-wise are sometimes 3x the amount of cereal despite having 1/2 the volume in packaging.

  • http://www.mindyourdecisions.com Presh

    @Tiffany: Thanks for the details on your experience with warehouse pricing. I never wrote them down, but I always had a suspicion.

    And just to put out the other side, warehouses are great for large quantities of alcohol and gourmet products like pine nuts and sundried tomatoes.

    @naree: I didn’t even think about the environmental effect, but that is totally true. The companies are either making us buy lots of smaller boxes or less-than-full large boxes. This is a shame.

    @Rohit: I bet it did not settle that much. And even if cereal could settle, can you explain how granola bars would settle?

    Good point about high-fiber cereals since they are dense and hence have a lot of weight per volume.

  • Kyle

    I’m willing to bet that the granola bars box was labeled with reference to how many bars were contained within the box itself. Though it was just a clever ploy to make not much more look like much more, the only thing that the granola makin’ company can truly be chided for is wasting their own money on extra packaging materials while hoping for a percentage of their targets (albeit a large one, I do not pity a fool) to fall for the deceit.

  • http://www.mawsoft.com/blog RohoMech

    So there’s two other things about larger boxes that might be of interest:

    1.) Sucking up shelf-space away from competing products.

    2.) Larger images attract people better, some products, the box is the best ad.

    @Kyle – good call on the number of bars in the box, it’d be great if someone started selling 30 bars! but each was 1/4 the normal size (they’ll be fun-sized!) or some nonsense like that.

  • http://www.mindyourdecisions.com Presh

    @Kyle and Rohit: great points.

  • http://modite.com/blog Rebecca Thorman

    Interesting. I always try to look at the price per oz or whatever they list on the price tag and grab the cheapest :)

  • Kyle B

    Another example of this practice is yogurt containers. A few years ago, yogurt in portioned containers were the size of 6 oz each. Then over night, without the price changing at all, the industry moved to 4 oz containers. I think they look smaller, but the dieting community loves them.

    Kyle B

  • http://www.mindyourdecisions.com Presh

    @Kyle B: This is a great example of how companies raise the cost without raising the price consumers see.

  • Joon

    I guess I’m strange because I never really notice the size of boxes. In general I think I’m a very poor judge of volume and have always defaulted to unit costs. Also I don’t eat enough cereal to justify the big box anyways.

  • Don Vaught

    The usual explanation from industry folks (my mother-in-law worked in Quality Assurance for over 20 years at large bakery producers) is that the increased packaging is necessary to insure safe delivery of the product. Completely full bags, while environmentally best in a perfect world, end up making for lots of crushed product. Crushed product leads to upset customers who choose against the brand. The only real idea used as to how to protect the product is to have air in the bag to protect against shocks. They can’t control where the product goes inside the air although it usually ends up smooshed in the bottom due to this newfangled gravity, so they just add an amount of air to try to offset the volume, hence the more than linear increase in the empty space. Emptiness is saddening, especially in the midst of an existential crisis, and maybe it is partially due to companies manipulating our hujumbo buying impulses, but it also makes for products that look like they should. The best engineer’s answer: new fractal boxes. The best economist’s answer: just keep coming back to me on that. The best accountant’s answer: what do you want to hear?

  • http://www.mindyourdecisions.com Presh

    @Don Vaught: Thanks for sharing the industry perspective; the safety mechanism of extra air sounds very interesting.

    Your closing joke is hilarious.

  • Livvymom

    another way to think of it: that cereal is processed junk – especially a lot of sugar. Your best bet is to bypass it altogether. Hard boiled eggs would be a much better investment. And it’s hard for a store to try to deceive you on how many eggs you get per carton

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