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Slack Fill: What Is It and Why Is It Allowed?

All That Empty Space

Slack Fill

Have you ever opened a new bag of potato chips and been disappointed when it seems like half of the chips are missing? Of course you have, we’re all human: we love salty treats and don’t enjoy it when it seems like we’re getting a bad deal. Those “missing” potato” chips are a perfect example of slack fill. Slack fill is defined as the empty space in a package filled to less than its capacity. Simple enough and, unfortunately for snack time but fortunately for us, not all slack fill is an issue.

Slacking Off

With very few exceptions, every single package is going to have at least some slack fill. The reason for slack fill is nothing nefarious; in almost all cases it is simply a side effect of practicality when packaging or shipping.

There are two qualifying circumstances where slack fill becomes an issue. The first is “misleading packaging”, or when the container does not allow the consumer to see what’s inside. This could be any solid item, like a cardboard box, an opaque plastic that blurs the contents, or perhaps a label that hides the slack fill on a clear container. The second distinction is if the slack fill is defined as “functional” or “non-functional” space.

The Big Six

Slack Fill

Several laws have been passed in order to protect consumers from misleading packaging and non-functional space. The FDA (Food and Drug Administration) has designated six exceptions where slack fill in misleading containers is considered “functional space” and is therefore legally compliant. Those exceptions (and brief accompanying examples) are:

1. Protection of the contents

Remember our potato chips? The slack fill there is necessary to make sure the chips don’t break during shipping and handling

2. Required by the machine used to fill the package

Automated factories might not have the ability to fill containers to the brim

3. Unavoidable settling of contents during shipping

This could apply to spherical products placed inside of a rectangular shipping container and subsequently moving around while in transit

4. Need for package to perform specific function

For many microwaveable or frozen foods, there needs to be additional space for the consumer to add water or some other substance for final preparation of the contents

5. If the packaging has specific value

Any souvenir cups or items that have value apart from the content they hold

6. Inability to reduce the size of the package

Medical pills or tablets require readable labels that can only be so small while still following other FDA guidelines

Rise in Awareness of Slack Fill

Slack Fill

Recently, there has been a rise in consumer class action lawsuits from a small group of lawyers. There is little reason to worry, because while social media may enable certain lawsuits to go viral, the courts have found them almost entirely without merit.

However, it is often useful during the design and in the course of using any packaging to perform a slack-fill self-audit with an independent legal team and packaging expert. Sometimes, it can be as easy as adding a “Fill Line” to an already compliant package to make sure there will be no confusion by the consumer.


If you’re looking to maximize your packaging and minimize stress, GCB Solutions is here to help. Our vast experience can assist at every step in the process from initial design to final production. Call us at (904) 263-2804 or schedule a free consultation, today.


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