New York has no statewide limit on how long a knife blade can be, but two local layers change that answer fast. In New York City, any blade of four inches or longer is illegal to carry in public, and in any federal building anywhere in the state, the cutoff drops to two and a half inches. So the honest answer to what size knife is legal to carry in New York depends entirely on where you are standing when someone asks.
Size is also only half the question. Four specific types of knives are banned statewide no matter how short the blade, and carrying any knife with intent to harm someone is a separate crime on top of that.
Statewide: No Length Limit, But Four Knives Are Always Illegal
Outside New York City, state law sets no numeric blade-length cap for ordinary folding knives, fixed-blade knives, or utility knives. A chef can walk home with a ten-inch kitchen knife and be within the law.
What the state does ban outright, regardless of size, is a short list of knife types under Penal Law 265.01. These are called per se weapons, and possession alone is a crime:1New York State Senate. New York Penal Law 265.01 – Criminal Possession of a Weapon in the Fourth Degree
- Switchblade: a knife whose blade opens automatically when you press a button, spring, or similar device on the handle.
- Pilum ballistic knife: a knife whose blade can be launched from the handle by a button, lever, or spring.
- Metal knuckle knife: a weapon that works as both knuckles and a knife.
- Cane sword: a blade concealed inside a walking cane.
A two-inch switchblade is just as illegal as a six-inch one. There is no size exception for these four categories, and the ban reaches into your home, not just your pocket.
One category that used to trip people up, the “gravity knife,” was removed from the per se list in 2019.2New York State Senate. Assembly Bill A5944 Ordinary folding knives that an officer can flick open with a wrist snap are now legal under state law.
Intent Still Matters for Any Knife
The same statute makes it a crime to carry any knife, of any size, with intent to use it unlawfully against another person.1New York State Senate. New York Penal Law 265.01 – Criminal Possession of a Weapon in the Fourth Degree Daggers, dirks, machetes, razors, and stilettos are all legal to possess until that intent enters the picture.
In practical terms, a large or menacing-looking blade gives police more reason to question what you plan to do with it, even in a part of the state with no size cap. Being within the statute is not the same as avoiding a stop.
New York City: Under Four Inches, Fully Concealed
New York City Administrative Code 10-133 adds the rule most people miss. It is illegal to carry any knife with a blade of four inches or longer in any public place, street, or park within the city.3Justia. New York City Administrative Code 10-133 – Possession of Knives or Instruments Intent does not matter here. A carpenter heading to a job site with a legitimate five-inch folder is still in violation.
The city also bans carrying any knife in open view, regardless of blade length. A pocket clip showing above your pocket, the top of a handle poking out of a bag, any visible portion of the knife, counts as a violation on its own.3Justia. New York City Administrative Code 10-133 – Possession of Knives or Instruments The two rules are enforced independently, which means a legal three-inch blade can still get you charged if the clip is visible.
Work and Transport Exceptions
The city code recognizes that people carry knives for legitimate reasons. The display ban does not apply if you are actively using the knife for a lawful purpose, or transporting it directly to or from a job site or an activity like hunting, fishing, or camping.3Justia. New York City Administrative Code 10-133 – Possession of Knives or Instruments If you are moving a knife to or from a place of purchase, sharpening, or repair, it must be packaged so it is not easily accessible during transport.
These are defenses after a stop, not reasons an officer will walk past you. If you carry a knife for work in the city, the safer practice is to keep it fully concealed in a bag or toolbox, and keep any pocket-carry blade under four inches.
Federal Buildings: Under Two and a Half Inches
The strictest size rule anywhere in New York applies inside federal buildings. Under 18 USC 930, knives with blades of two and a half inches or longer are treated as dangerous weapons and prohibited in any building owned or leased by the federal government where federal employees work. A pocket knife with a blade shorter than two and a half inches is the only exception.4Office of the Law Revision Counsel. 18 USC 930 – Possession of Firearms and Dangerous Weapons in Federal Facilities
Post offices, Social Security offices, federal courthouses, and similar facilities all fall under this rule. If you carry a pocket knife daily and visit any of these regularly, either keep the blade under two and a half inches or leave it in the car.
Places Where No Knife Is Legal
A perfectly sized, perfectly legal knife becomes contraband in certain places. Blade length does not help you here.
- NYC Transit: The NYPD states that no knives should be carried anywhere within the NYC Transit system, including subways and buses.5NYPD. FAQ Knives
- Schools: School districts across New York prohibit knives of any size on school grounds or school buses through their codes of conduct, and bringing one can lead to criminal charges depending on circumstances.
- Courthouses: All New York court facilities screen for weapons at entry, and knives are prohibited.
- Airports: TSA prohibits all knives in carry-on bags, with the narrow exception of rounded, non-serrated butter knives. Knives can go in checked luggage if sheathed or securely wrapped.6Transportation Security Administration. Sharp Objects
If You Are Under 16
Penal Law 265.05 prohibits anyone under 16 from possessing a “dangerous knife.” The statute does not fix a numeric blade length, so enforcement turns on context. A small pocket knife used for ordinary tasks is unlikely to draw a charge; a large fixed-blade knife carried through a park or into a school can, even when the same knife on an adult would be legal.
Penalties If You Get It Wrong
The state charges are the ones to take seriously. Possessing a per se illegal knife, or carrying any knife with intent to harm, is Criminal Possession of a Weapon in the Fourth Degree, a Class A misdemeanor punishable by up to 364 days in jail.1New York State Senate. New York Penal Law 265.01 – Criminal Possession of a Weapon in the Fourth Degree7New York State Senate. New York Penal Law 70.15 – Sentences of Imprisonment for Misdemeanors
If you have any prior conviction, not just a weapons offense but any crime, that same charge becomes Criminal Possession of a Weapon in the Third Degree, a Class D felony carrying up to seven years in prison.8New York State Senate. New York Penal Law 265.02 – Criminal Possession of a Weapon in the Third Degree9New York State Senate. New York Penal Law 70.00 – Sentence of Imprisonment for Felony A years-old shoplifting conviction is enough to turn a knife misdemeanor into a felony.
New York City’s administrative code violation is a separate, smaller matter: up to a $300 fine, up to 15 days in jail, or both.10American Legal Publishing. NYC Administrative Code 10-133 – Possession of Knives or Instruments It is still an arrest and still a record.
Legal Blade Length by Location
- New York State outside NYC: no numeric blade-length limit. Avoid the four banned knife types. Carry without intent to harm.
- New York City: blade must be under four inches, and the knife must be fully concealed.
- Federal buildings anywhere in New York: blade must be under two and a half inches.
- NYC Transit, airports, courthouses, and schools: no knives of any size.
State law does not stop other municipalities from passing their own knife rules, so if you travel across New York the safest default is a folding knife with a blade under four inches, kept fully out of sight, and left behind before you enter any government building or transit system.