Air to Spare: Why Are Product Bags, Boxes Not Full?

Everyone has opened a box or bag, only to find that the product purchased doesn't even begin to fill the package.

It raises interesting questions: Why does a vitamin bottle rattle when you shake it? Or why does pasta mix fill only the bottom of the box?

Brian Wansick, a Cornell University professor and author of "Mindless Eating," said studies show consumers are attracted to big boxes and bags, even if they don't actually contain more food.

"One of the things we found ... is that people determine the value of a product based on the size of the package -- the bigger the size of the package, the more value they believe it is," Wansick said.

VIDEO: Air to Spare in product packagingPlay

But Wansick said it is not an evil plot against consumers.

"As Americans, we love a good conspiracy story, but this is one story where there is no conspiracy," Wansick said. "There is actually empty space in these packages ... for our benefit."

By law, manufacturers are not allowed to build a large amount of black space into their packages unless there is a good reason.

It turns out there are lots of good reasons, according to a report by Consumer Reports magazine.

"Slack fill rules state that you can have excess slack fill if it pertains to, say, protecting the contents inside, if it has to accommodate the machinery that actually boxes, bags and bottles this stuff, if it provides some sort of value added quality," said Consumer Reports senior editor Tod Marks.

Frito Lay explained that potato chips are fragile, and all that air in the bag acts as a cushion that keeps them from crumbling.

Potato chips are sold by weight, not volume. So was the weight accurate?

"Don't worry, we found in every instance manufactures were delivering what they promised in terms of the contents, so you are not being shortchanged," Marks said.

Why Does Rice Settle to the Bottom of the Box?

Most people have noticed that Uncle Ben's rice sinks to the bottom of its box.

According to Uncle Ben's, its whole grain rice used to be puffed, but became puny after a reformulation.

It weights the same, but the size is different.

The company changed the product, but not the package, to avoid having to retool its manufacturing plant.

Looking at Ocean Premium Saline Nasal Spray, many people have wondered why the bottle takes up only half the box.

The company said it leaves space because it often includes a free sample of some other item, and it can't keep changing its packaging because stores need to plan their shelf space.

"Stores allocate shelf space to companies based on how much they are going to sell, and it's easier to get that shelf space allocation correct if you have boxes that are all the same size because you are not playing a game of Russian roulette, moving out one size (and) bringing in another," Marks said.

Too Much Packaging Upsets Green-Conscious Consumers

None of this sits well with green-conscious consumers, who are more upset about the fact there is too much packaging rather than not enough product.

For example, in Pepperidge Farm Texas Toast there is more box than there is bread.

It turns out Pepperidge Farm is in the midst of analyzing its entire product line to look for ways to minimize its packaging.

The company said it tries to make its products more environmentally-friendly with every redesign.

And finally, vitamin bottles are required to include a lot of information on the label, which means it must be big enough for consumers to read.

Consumers can become better shoppers if they look at the weight and unit prices of the products, not just the size of the box or bag.

So when it comes to product packaging, think of it this way: As long as your belly is full, it doesn't matter if the box is.

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