No knife of any size goes through a TSA checkpoint in your carry-on or your pocket: not a Swiss Army Classic, not a keychain Microblade, not a two-inch slip joint. Any knife can go in a checked bag. That is the whole rule for U.S. domestic flights, and this guide covers the details: what counts as a knife, what happens if you forget, how to pack one, and why international rules are stricter.
Carry-on: no knives
TSA prohibits knives in carry-on bags and on your person, with one exception: plastic or round-bladed butter knives. Blade length does not matter, locking does not matter, and "it's just a keychain" does not matter. Scissors under four inches from the pivot and multitools with no blade are allowed, at the screening officer's discretion.
Checked bags: yes
Any knife, sheathed or wrapped so it cannot cut a bag inspector. Put it in a hard case or its sheath, in a pocket of the checked bag you will remember. A kydex or leather sheath is ideal.
If you forget
The checkpoint will find it. Your options: go back and check the bag, hand the knife to someone not flying, mail it home if the airport has a kiosk, or surrender it. That last one is how a lot of Penguins end up in TSA auction lots. Check your pockets and your keys the night before; the Microblade on a keychain is the one people forget.
International
Most countries match or exceed the U.S. rule for carry-on. The bigger issue is carrying the knife on the ground at your destination: the UK bans locking knives and anything over three inches in public; several EU countries restrict one-hand-opening and locking folders; Japan limits blade length. A non-locking slip joint under three inches, like the ROGAN UK-EDC friction folder or a Swiss Army knife, is the safest thing to travel with abroad. Check the destination before you pack.
Multitools
Same rule: a multitool with a blade is checked-bag only. Bladeless multitools are permitted in carry-on at the officer's discretion. See the Leatherman travel guide linked below.
Packing checklist
- Knife closed, in a sheath or case.
- In checked luggage, in a zip pocket.
- Keychain knives off the keyring.
- Destination law checked for locking and length limits.
Frequently asked questions
Can you bring a pocket knife on a plane?
In checked luggage, yes. In carry-on or on your person, no, regardless of size.
Can you bring a pocket knife in a checked bag?
Yes, sheathed or wrapped.
Can I bring a Swiss Army knife on a plane?
Checked bag only; it has a blade.
What happens if TSA finds a knife in my carry-on?
You can check it, hand it off, mail it, or surrender it.
Can I carry a pocket knife in Europe or the UK?
Rules are stricter; the UK bans locking knives in public. A small non-locking knife is safest.
The bottom line
Checked bag, in its sheath, keychain knives off the ring. A kydex sheath makes the packed knife safe for the inspector.
Related reading
Can you bring a Leatherman on a plane?
Is it legal to carry a pocket knife?
Best Swiss Army knife for EDC
