TSA Rules Checker

Search 60+ items, "water bottle", "lithium battery", "gun", "cheese", "weed" (federal answer), get carry-on / checked / forbidden with the exact limits.

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—the 3-1-1 rule, decoded

—liquids rule post-security

—the lithium battery rules that catch everyone

How the rules work (TSA 34 CFR 15 / 49 CFR, 2026)

3-1-1: liquids/gels/aerosols ≤ 3.4 oz (100 ml) per container, one quart bag, one bag per passenger. "3.4 oz" is container size, not content, a 6 oz shampoo bottle 10% full is confiscated. Exceptions: prescription meds (liquid form allowed in reasonable quantity, declare), baby formula/food (allowed exceeding 3.4 oz, declare for screening), frozen ice packs (allowed if frozen solid; TSA screeners judge "partially melted" by feel, they're allowed fully frozen).
Lithium: spare (loose) lithium-ion ≤ 100 Wh carry-on only, max 2 spares for consumer devices (the rule that kills vaper/battery-brick packing); 101–160 Wh with airline approval (pro video batteries); devices installed in equipment: fine checked. Power banks = spare batteries: carry-on only. Pure lithium metal (non-rechargeable) 2 g/spare.
Firearms: checked, locked hard case, unloaded, declared at counter, the one federal procedure with a receipt signature. Ammunition: checked, in original box, ≤ 11 lb per passenger in checked.
The "it's in the gray zone" list is where people get pulled: self-defense spray (checked only, ≤ 4 oz with safety lock), safety matches (1 book on person, strike-anywhere forbidden), nail polish (carry-on fine, acetone remover NO), sharp knives (checked only, boxed blades; 4" plastic travel knives gray), hockey stick/golf club (carry-on OK now, post-2019, people still get them bin-binned by over-eager screeners).

TSA decides at the checkpoint, and local law layers on top (cannabis is legal at 25 states' pot shops but a federal airport crime; firearms in airport sterile areas follow state too). International departures add the destination country's rules, e.g. many countries ban alcohol in checked inbound. This is a planning tool; the checkpoint officer is the law.

Frequently asked

Can I bring a lithium battery on a plane?

Installed in a device: carry-on or checked. Spare/loose batteries and power banks: carry-on only, consumer sizes (≤100 Wh), max 2 loose spares. Checked spare lithium batteries = the #1 confiscated category and a fire risk.

Is water allowed through TSA?

An empty bottle through the checkpoint is fine; filled >3.4 oz is bin. After security: buy/bottle freely. Medically necessary water (with IV bags, declare) and baby/child water over 3.4 oz are allowed declared.

What foods can I bring on a plane?

Solid food: anything (sandwiches, cookies, cheese, cut fruit). Spreads, dips, jams, honey, hummus, creamy cheeses, soup, salsa = liquids under 3-1-1 (3.4 oz in the quart bag). Domestic flights = fine at the checkpoint; international arrivals = CBP agriculture rules on fresh fruit/meat.