Almost every TSA guide is written about the carry-on. That makes sense, because the carry-on is what goes through the checkpoint. But the checked bag has its own rulebook, it is enforced by a different process, and getting it wrong costs you more: a delayed bag, a confiscated item, a cut lock, or in the worst cases a fine.

Here is what actually applies to checked luggage, what surprises people most, and how to pack so your bag arrives with everything still in it.

The One Rule That Reverses Everything You Know

For carry-on bags, the mental model is simple: sharp, heavy, and flammable things are banned. For checked bags, that flips for some categories and holds for others.

Things that are banned from the cabin but allowed in checked bags: full size liquids, knives, scissors of any length, tools over 7 inches, baseball bats, razors with exposed blades.

Things that are allowed in the cabin but banned from checked bags: lithium ion power banks, spare lithium batteries, e-cigarettes and vapes, and anything else with a loose lithium cell.

That second list is the one that catches people. The instinct is that the “dangerous” battery belongs in the hold, away from passengers. The FAA rule is the exact opposite, and the reasoning is straightforward: a lithium battery fire in the cabin can be seen and extinguished within seconds, while the same fire in the cargo hold can burn undetected. Our electronics guide covers the battery rules in full, including watt-hour limits.

What Is Banned From Checked Bags Entirely

These items cannot fly in the hold under any circumstances:

  • Spare lithium batteries and power banks. Carry-on only, no exceptions.
  • E-cigarettes and vaping devices. Carry-on only, and you may not charge or use them in flight. See our vape and lighter guide.
  • Torch lighters and strike anywhere matches.
  • Flammable liquids and gases, including camp stove fuel, lighter fluid, paint thinner, and most aerosols beyond limited personal care quantities.
  • Fireworks, flares, sparklers, and gunpowder.
  • Bleach, pool chemicals, and corrosives.
  • Recalled or damaged lithium batteries of any kind.

The consequence for these is not just confiscation. Undeclared hazardous materials can carry civil penalties running into the thousands of dollars, and the airline can offload your bag.

What Is Allowed in Checked Bags but Not Carry-On

This is where the checked bag earns its keep:

  • Liquids in any size. The 3-1-1 rule applies only to the cabin. Full size shampoo, sunscreen, and a liter of contact solution are all fine in the hold.
  • Alcohol up to 5 liters per passenger between 24 and 70 percent ABV, in unopened retail packaging. Above 70 percent ABV is banned outright, and under 24 percent has no quantity limit from TSA. Details in our alcohol guide.
  • Knives, scissors, razor blades, and multi-tools, ideally sheathed or wrapped so they do not injure a screener or baggage handler.
  • Tools of any length, including drills, wrenches, and crowbars.
  • Sporting goods that count as bludgeons in the cabin: bats, clubs, cues, ski poles.
  • Firearms and ammunition, but only under a strict declaration and locked hard case procedure. This is the one category where getting it wrong is genuinely serious, so read our firearm rules guide before you pack one.

How Checked Bags Are Actually Screened

Your checked bag does not go through the checkpoint X-ray. After you drop it at the counter, it travels to an inline explosive detection system, essentially a large CT scanner. Most bags clear automatically in seconds.

If the scanner flags something, the bag is diverted for a physical inspection. A TSA officer opens it, examines the flagged area, repacks it, and leaves a printed Notice of Baggage Inspection inside. That slip is routine and does not mean you did anything wrong. Dense food, tightly packed clothing, and stacked electronics all trigger it regularly.

Two practical consequences:

  • Pack so a stranger can repack it. A bag inspected at 5am by a rushed officer will not be refolded the way you left it. Use packing cubes and keep fragile items cushioned but visible.
  • A physical inspection takes time. If you check a bag close to the cutoff and it gets flagged, it can miss the flight even though you did not. This is a real argument for arriving early, which our airport arrival timing guide covers in detail.

TSA Approved Locks, and Why the Distinction Matters

A standard padlock on a checked bag will be cut off if TSA needs to inspect it. They are not required to preserve your lock, and they will not replace it.

A TSA approved lock has a universal master keyway that lets an officer open it with a passkey, inspect the bag, and relock it. It is the only kind worth using on checked luggage.

Two caveats worth knowing:

  • TSA approved locks are a deterrent against casual tampering, not real security. The master key designs are widely known. Do not rely on one to protect anything genuinely valuable.
  • The same lock on a firearm case is a violation. Firearm cases must be locked so that only you have the key or combination, which means an ordinary non-TSA lock is specifically required there.

TSA permits these, but experience says keep them with you:

  • Prescription medication. If your bag is delayed, so is your medication. Keep it in the cabin, in its labeled container. Our medication guide covers the checkpoint rules.
  • Laptops, cameras, and anything else expensive. Airline liability limits for checked baggage are far below the replacement cost of good electronics.
  • Jewelry, cash, and important documents. Airline contracts of carriage generally exclude cash from baggage liability. If you are carrying a large amount, read our guide to how much cash you can fly with first.
  • Car keys and house keys. A single key with a transponder can cost hundreds to replace, and you need it to get home.
  • A change of clothes. Bags do go missing. One spare outfit in the cabin is cheap insurance.

Packing Order That Saves Time at Both Ends

  1. Batteries and vapes out first. Sweep the checked bag for anything with a lithium cell and move it to your carry-on before you close the zipper.
  2. Liquids into the checked bag. Anything over 3.4 ounces belongs here, sealed in a bag in case of pressure leaks.
  3. Sharp items sheathed and centered, wrapped in clothing away from the walls of the bag.
  4. Leave it unlocked or use a TSA approved lock. Never a standard padlock.
  5. Weigh it before you leave. Overweight fees are an airline rule, not a TSA one, but the standard limit is 50 pounds on most domestic economy fares.

Frequently Asked Questions

Can I put a power bank in my checked bag?

No. Power banks and all spare lithium batteries are carry-on only under FAA rules. If a bag containing one is discovered, it will be pulled and the battery removed, which can delay the bag past your flight.

What does the TSA notice in my suitcase mean?

It means your bag was flagged by the scanner and opened for a physical inspection. It is routine and happens to a large number of bags. It is not an accusation, and no follow-up is required from you. If something is missing or damaged after an inspection, that is a TSA claim rather than a lost item report; our TSA lost and found guide covers how to file it.

Are TSA approved locks actually required?

No, locks are optional. But if you lock a checked bag with anything other than a TSA approved lock and the bag is selected for inspection, the lock will be cut off and not replaced.

Can I pack liquids over 3.4 ounces in a checked bag?

Yes. The 3-1-1 rule applies only to carry-on bags. Full size liquids are fine in checked luggage, with the exception of alcohol above 70 percent ABV and flammable or corrosive liquids, which are banned.

Can I pack powder in a checked bag?

Yes, and there is no quantity limit. The 12 oz powder threshold that triggers separate screening applies only to carry-on bags, so a full tub of protein powder or a large container of baby powder belongs down below. Keep it in labeled retail packaging, since a large unlabeled bag of powder is a reliable inspection trigger. Our guide to the TSA powder rule covers the carry-on side.

Can I check a bag with food in it?

Yes, and solid foods are unrestricted. Dense items like large blocks of cheese or bags of coffee are common inspection triggers, so expect the occasional notice. International arrivals are a separate matter, since agricultural rules on produce, meat, and dairy are enforced by customs, not TSA. Our food guide covers both.

Does checking a bag get me through security faster?

Often yes, indirectly. A lighter carry-on means fewer bins, fewer items to unpack, and a lower chance of a bag check at the checkpoint. It also means arriving earlier for the bag drop cutoff, so the net time saving depends on your airport. Our 12 tips for faster screening covers the rest.

Check the Line Before You Go

Packing a checked bag correctly gets it to the destination. Knowing the checkpoint wait gets you there on time. Bag drop cutoffs are typically 45 minutes before departure domestically, and a long security line after that cutoff leaves you no margin.

Look up your airport on Airport TSA Times to see when its checkpoints are busiest, from TSA’s own hourly counts, so you know how much buffer you need.