How Big of a Knife Can You Carry in Washington?

There is no statewide maximum blade length for a knife in Washington, so the honest answer to how big of a knife you can carry in Washington depends on three things: which city you are in, whether the knife is one of the banned types, and whether you are carrying it openly or concealed. Under state law alone, you can openly wear a fixed-blade knife of any length. Step into Seattle, Tacoma, or Vancouver, and the practical ceiling drops to 3.5 inches.

The 3.5-Inch City Limit

Washington does not preempt local knife rules. Cities and counties set their own, and the most common restriction is a ban on carrying any knife with a blade longer than three and one-half inches. Seattle, Tacoma, and Vancouver each define a “dangerous knife” that way, and each ordinance applies to both open and concealed carry. A 5-inch hunting knife that is perfectly legal on your belt under state law can still get you cited inside those city limits.

Other Washington municipalities may have their own rules, and they are not always identical. Before you carry a large knife anywhere in the state, check the local municipal code. State-level freedom to openly wear a knife of any length does not override a city ordinance that says otherwise.

Knives That Are Illegal at Any Size

Some knives are illegal to make, sell, or possess in Washington no matter how short the blade. RCW 9.41.250 bans spring blade knives, defined as any knife with a blade that opens automatically through a spring or other mechanical device. The ban also reaches knives that open by gravity or centrifugal force, which covers butterfly knives and gravity knives.¹

Assisted-opening knives with a bias toward closure are treated differently. If the knife has a spring or detent designed to keep the blade shut, and you have to push on the blade itself to overcome that resistance, it is not a spring blade under the statute.¹ Most popular assisted-opening folders on the market fall on the legal side of that line. The distinction is whether you use your hand on the blade to open it, or press a button on the handle that launches it.

The only statutory exception for possessing an actual spring blade knife applies to law enforcement officers on duty or transporting the knife to and from storage.¹ For everyone else, possession alone is a crime.

Open Carry vs. Concealed Carry

Size matters less than visibility under state law. Openly carrying a common knife is not restricted by any state statute. You can wear a large fixed-blade hunting knife on your hip because the knife is visible and you are not being furtive about it.

Concealment is where the state statute bites. RCW 9.41.250 makes it a crime to furtively carry with intent to conceal any dagger, dirk, or other dangerous weapon.¹ “Dagger” and “dirk” generally mean double-edged stabbing knives, but the catch-all “other dangerous weapon” has no defined blade length. Courts look at the totality of the situation: the type of knife, how it was carried, and the apparent intent.

A folding pocket knife clipped inside your pocket for daily tasks is not typically treated as a concealed dangerous weapon. Context changes that. The same knife carried at 2 a.m. near a bar after an argument looks different to a police officer and a judge than it does clipped to your jeans at a campsite. A short blade does not automatically keep you safe from a concealment charge.

Separate from concealment, RCW 9.41.270 makes it a gross misdemeanor to carry, exhibit, or draw any knife in a manner, at a time and place, that either shows intent to intimidate someone or reasonably warrants alarm for others’ safety.² This applies to any cutting or stabbing instrument, and it does not care whether the knife itself is legal to own.

Places Knives Are Off-Limits

Even a state-legal, city-legal knife cannot go everywhere. Under RCW 9.41.280, it is illegal to knowingly possess a dangerous weapon on the grounds of any public or private elementary or secondary school, on school-provided transportation, or at any facility being used for a school event.³

RCW 9.41.300 prohibits weapons in several other locations:⁴

The restricted-access areas of jails, law enforcement facilities, and places used to confine people under court order. Public entry areas are not included.
Courtrooms, jury rooms, judges’ chambers, and adjacent corridors.
The portion of any bar or tavern that the state liquor and cannabis board classifies as off-limits to people under 21.

Federal buildings follow federal rules. Under 18 U.S.C. § 930, a pocket knife with a blade shorter than 2½ inches is exempt from the federal ban on dangerous weapons in federal facilities. Anything longer, with a locking mechanism, or a fixed blade can be treated as a dangerous weapon in a federal courthouse, post office, or government office building, with penalties up to one year in federal prison.⁵ National park land generally follows the knife laws of the surrounding state, but individual monuments and high-security sites within parks can impose tighter rules.

At Sea-Tac and every other airport, the TSA prohibits all knives in carry-on bags, with a narrow exception for rounded, blunt-edged, non-serrated blades like butter knives and plastic cutlery. Knives of any type can go in checked luggage as long as they are sheathed or securely wrapped, and the final call on any borderline item belongs to the TSA officer at the checkpoint.⁶

Penalties

Most knife offenses under state law are gross misdemeanors, including possessing a prohibited spring blade knife, furtively concealing a dangerous weapon, and displaying a knife in an intimidating manner.¹ A gross misdemeanor in Washington carries up to 364 days in county jail, a fine of up to $5,000, or both.⁷

Possessing a dangerous weapon on school grounds is a misdemeanor for a first offense, punishable by up to 90 days in jail and a $1,000 fine. A second or subsequent school-grounds violation becomes a gross misdemeanor with the heavier penalties above.³

City ordinance violations carry their own penalty schedules, which vary by municipality. If the circumstances involve assault, robbery, or threats, a knife charge can escalate quickly into felony territory with substantially longer sentences.

1
Washington State Legislature. Washington Code RCW 9.41.250 – Dangerous Weapons—Penalty
2
Washington State Legislature. RCW 9.41.270 – Weapons Apparently Capable of Producing Bodily Harm
3
Washington State Legislature. RCW 9.41.280 – Possessing Dangerous Weapons on School Facilities
4
Washington State Legislature. Washington Code RCW 9.41.300 – Weapons Prohibited in Certain Places
5
Office of the Law Revision Counsel. 18 U.S. Code 930 – Possession of Firearms and Dangerous Weapons in Federal Facilities
6
Transportation Security Administration. Knives
7
Washington State Legislature. Chapter 9A.20 RCW – Classification of Crimes