What Not to Pack: TSA Rules for O'Hare and Midway Travelers

The Liquids Rule, Plainly

The 3-1-1 rule still governs carry-on liquids: containers of 3.4 ounces (100ml) or less, all fitting in one quart-sized clear bag, one bag per passenger.

The part people misunderstand: it's the container size that matters, not how much is in it. A half-empty 8-ounce bottle of shampoo doesn't qualify, even with only 3 ounces left inside.

"Liquids" is broader than it sounds. It includes gels, aerosols, creams, and pastes — so toothpaste, sunscreen, peanut butter, yogurt, and mascara all count.

Exceptions exist for medically necessary liquids, baby formula, and breast milk, which can exceed 3.4 oz but should be declared at the checkpoint for separate screening.

Batteries: The Rule That Runs Backwards

This one catches people because it's the opposite of the usual pattern. Most restricted items go in checked bags. Lithium batteries and power banks must go in your carry-on — they're prohibited in checked luggage, because a fire in the cargo hold can't be responded to the way one in the cabin can.

• Portable phone chargers and power banks
• Spare lithium batteries
• Most e-cigarettes and vaping devices

If you're checking a bag with a battery-powered device inside, that's generally fine when the battery is installed. It's the spare, loose batteries that must travel with you.

Sharp Objects and Tools

Generally checked bags only:

• Knives of nearly any kind, including pocket knives and multi-tools with blades
• Scissors with blades longer than 4 inches (shorter ones are typically permitted in carry-ons)
• Razor blades and box cutters (disposable razors are fine)
• Most tools longer than 7 inches
• Corkscrews with blades

The pocket knife or multi-tool forgotten in a bag's side pocket is probably the single most common cause of a checkpoint holdup — worth an actual check of every pocket before you leave.

Food and Drink

• Solid food is generally fine in carry-ons — sandwiches, baked goods, snacks, packaged items.
• Liquid and gel foods follow the 3-1-1 rule — soup, sauces, dips, yogurt, jam, honey.
• An empty water bottle is fine through the checkpoint, and both O'Hare and Midway have refill stations past security. A full one is not.
• Alcohol under 24% ABV has no quantity limit in checked bags; between 24% and 70% is limited; over 70% is prohibited entirely.

If you're bringing Chicago food home as gifts — deep dish, sauces, or anything similar — check whether it's a liquid or gel before assuming it can fly in your carry-on.

Sports and Hobby Gear

Most sporting equipment travels checked:

• Golf clubs, baseball bats, hockey sticks, ski poles
• Anything that could be used as a bludgeon, which is a broader category than it sounds

Some items have specific rules worth checking individually — camping stoves, aerosol paints, and anything with a fuel component are common problem cases.

Vehicle note: oversized items like golf clubs or ski bags also affect which vehicle you need for the ride to the airport. Mention them when booking rather than hoping a sedan trunk works out.

What People Actually Lose Most Often

• Full water bottles
• Oversized toiletries, especially sunscreen and hand sanitizer
• Pocket knives and multi-tools in bag pockets
• Snow globes (they're liquid-filled, and larger ones exceed the limit)
• Corkscrews with foil cutters

None of these are dangerous. They're just in the wrong bag.