11 TSA Rules That Most People Don’t Know (But Should)

Like me, you've probably experienced the pang of anxiety that comes when you're standing in an airport security line and suddenly wonder whether you remembered to take your laptop out of your bag or whether your toothpaste tube is too large. The rules for air travel seem to change all the time, and the sheer volume of regulations can make anyone feel like they're walking on eggshells. Interestingly, there are many surprising exceptions and specific TSA guidelines that most travelers don't realize exist. Being aware of these little-known rules won't just save you time at the checkpoint, but it might also save you from having to toss out an expensive souvenir or gift.

1. Solid-Frozen Liquids Are Fair Game

Have you ever had to throw out a perfectly good bottle of water in the TSA security line because it was over the 3.4-ounce limit? Did you know, however, that there’s a sneaky loophole that could have saved it? If your liquid is frozen solid—top to bottom—when you reach the checkpoint, TSA agents should generally let it through. It's a game-changer if you want to keep snacks cold or bring a favorite drink from home. Just make sure there isn’t any melted liquid at the bottom of the container, or it'll be treated like any other prohibited item and tossed.

2. Special Rules for Small Children's Essentials

Parents traveling with infants or toddlers don't have to worry about standard liquid restrictions when keeping their little ones fed. The TSA classifies breast milk, formula, and toddler drinks as "medically necessary liquids," meaning they're allowed in quantities exceeding 3.4 ounces. You don't even need to have your child with you to bring these items through security. Just be sure to inform the officer at the start of the screening process so they can set these items aside for separate inspection. It's a vital exception that makes family travel a lot more manageable.

3. Alcohol and the Mini-Bottle Rule

If you're hoping to bring a little liquid courage for your trip, you'll be happy to know that mini-bottles of alcohol are perfectly legal in your carry-on. As long as they fit inside your single quart-sized bag and contain less than 24 percent alcohol by volume, they're treated like any other liquid. However, there is a major catch that many people forget: FAA regulations strictly prohibit you from drinking your own alcohol while on the aircraft. Under U.S. law, you can bring the bottles to your destination (although local regulations may be a different story), but you'll have to consume them before you board or wait until you land to crack them open.

4. Tools Must Meet the 7-Inch Rule

You might assume all tools are banned from the cabin, but that isn’t the case for smaller hand tools. As long as your wrenches, pliers, or screwdrivers are 7 inches or shorter (measured from end to end), you're allowed to keep them in your carry-on bag. This is particularly useful for technicians or DIY enthusiasts who want to keep their essential gear close at hand. However, tools with sharp edges or power tools are still relegated to your checked luggage. Knowing what's allowed and what isn't can save you an awkward conversation about size—as well as a trip back to the check-in counter.

5. Knitting Needles Are Actually Welcome

If you're into crafts, you may worry that your hobby could be considered a security risk—but the TSA is surprisingly lenient when it comes to knitting and crochet. You're allowed to bring knitting needles and crochet hooks—of any material!—on the plane. While it’s always a good idea to use circular needles or plastic ones to avoid extra scrutiny, they are officially permitted in your carry-on bag. Just remember that small scissors must still have blades shorter than 4 inches to pass through. It’s a great way to stay relaxed and productive during a long-haul flight.

6. Lithium Batteries Belong in the Cabin

It might seem counterintuitive to put something potentially flammable in your carry-on, but loose lithium batteries are actually banned from checked luggage. Because these batteries pose a fire risk, the FAA requires them to be in the pressurized cabin, where the crew can respond quickly in an emergency. This rule applies to power banks and spare camera batteries as well. If you have a "smart bag" with a built-in battery, you’ll usually need to remove it before the airline will allow you to check the suitcase. Keeping them with you is the safest way to travel.

7. Your Goldfish Can Fly, Too

It sounds like a joke, but you can actually bring a live fish through security. While the 3.4-ounce liquid rule applies to almost everything else, the TSA makes an exception for live fish in water. The fish must be in a clear, spill-proof container—probably not a half-full water bottle—and an officer will inspect the water visually at the checkpoint. This is a helpful tip for travelers moving to a new home or those who just can't bear to leave their aquatic friends behind. It’s one of the more surprising ways the agency accommodates unique travel needs without compromising safety.

8. Musical Instruments Get Special Treatment

Musicians don't have to leave their prized possessions to the mercy of baggage handlers if they don't want to. Federal law and TSA guidelines allow for small musical instruments, like violins or guitars, to be carried into the cabin as long as there's room in the overhead bins. You should still check with your specific airline regarding their individual sizing policies, but security officers will generally work with you to ensure your instrument is handled carefully during the X-ray process. It’s always best to arrive early so you have plenty of time for this specialized screening. One exception is that you may be required to check large brass instruments.

9. Pies and Cakes Get the Green Light

If you want to bring a homemade dessert with you on your travels—for the holidays, a gift, or a tasty snack along the way—you don’t have to worry about the security bin. Unlike soups or jams, pies and cakes are considered solid foods and are allowed through the checkpoint. You should be prepared for the possibility that these items might require additional screening, so keep them easy to reach. Just remember that if your "pie" is actually a jar of pudding or has a very liquid filling, it might fall under the liquids rule. Sticking to traditional baked goods ensures a smooth process for everyone involved.

10. Medical Devices Are Exempt From Bag Limits

Traveling with a CPAP machine, life-sustaining medical equipment, or other assistive devices can be daunting, but the FAA provides clear protections for these items. A CPAP machine is allowed in your carry-on and, perhaps more importantly, it doesn't count toward your airline's carry-on bag limit. You’ll need to take it out of its carrying case for X-ray screening, but you can request that the officer use a clean pair of gloves or a fresh bin. Knowing your rights regarding medical devices ensures that you can travel safely with the health tools you need.

11. Handling Cremated Remains With Care

Dealing with the loss of a loved one is difficult enough without worrying about airport security. The TSA allows cremated remains in both carry-on and checked bags, though it strongly recommends carrying them with you in the cabin. To pass through the X-ray, the remains must be in a container made of a material like wood or plastic that allows the machine to see what's inside. Security officers are strictly prohibited from opening the urn, even at your request, so if the X-ray cannot clearly identify the contents, it won’t be allowed on the plane.

You can make your time in the TSA line a little less stressful—and your packing a little more precise—if you know the rules. That said, rules change often and, sometimes, abruptly. Before you head out on your next trip—which you can map out with Only In Your State’s itinerary planner—take a quick second to double-check the latest updates on the TSA website to ensure your journey is as smooth as possible. A little bit of research goes a long way toward ensuring you spend less time in security and more time enjoying your destination.