Legal Carrying Knife Laws in the U.S.: What You Need to Know

Carrying a knife can be perfectly legal—or a serious offense—depending on your location, the knife type, and its blade length. U.S. knife carrying laws vary widely by state, and sometimes even by city. This guide explains the essentials of legal carrying knife rules, including legal length of knife limits, prohibited styles like switchblades, and whether certain knives count as weapons.

1. Why Knife Laws Are Complicated

Unlike firearms, knives are regulated at multiple levels—federal, state, and municipal. That means a knife that’s legal in one state could be an arrestable offense in the next. There are no universally applied knife size laws in the U.S., so it’s critical to know your area’s rules.

The factors that determine legality usually include:

Blade length (e.g., legal pocket knife length)
Opening mechanism (manual, assisted, automatic, OTF knives)
Intended use
Location restrictions (schools, government buildings, airports)

2. Legal Knife Blade Length and Size Limits

One of the most common questions is: What’s the legal size of a knife?

Most states set a legal knife blade length somewhere between 2.5 to 4 inches for public carry. Anything over that may be restricted or require specific circumstances (like hunting or fishing).

Examples:

California: Under 2 inches for concealed automatic knives; open carry allowed for larger fixed blades.
Texas: No statewide length restriction for most knives.
New York: Folding knives under 4 inches generally legal, but local laws apply.

If you’re wondering, “Can I carry a pocket knife?”, the answer depends on both knife size laws and the type of knife.

Everyday Carry Knife with Leather Sheath and 2.5-Inch Damascus Steel Blade

3. Are Pocket Knives Legal?

In most states, legal knives to carry include small folding knives with manual opening. But local ordinances can add restrictions. If you ask, “Is it against the law to carry a pocket knife?”, the answer could change between counties.

Common legal pocket knife criteria:

Manual folding blade
Under the state’s legal limit
Not disguised (e.g., knife hidden in belt buckle)

4. Is a Pocket Knife Considered a Weapon?

Legally, whether a pocket knife is considered a weapon depends on the situation. In most cases, a small folding knife for utility isn’t treated as a weapon. However:

If used in a threatening way, it becomes a weapon.
In some areas, any blade in certain places (like schools) is classified as a weapon automatically.

5. Illegal Knives in the U.S.

Some knives are prohibited entirely, regardless of blade length. These illegal knives often include:

Ballistic knives
Certain double-edged blades
Concealed blades disguised as everyday objects

If you hear about are machetes illegal, the answer is usually no for ownership, but yes for carrying in public without a specific lawful reason.

6. Are OTF Knives Legal?

OTF (Out The Front) knives—blades that eject straight from the handle—are a gray area. Many states consider them automatic knives, meaning they’re subject to switchblade laws.

Examples:

Are OTF knives legal in Washington State? No, state law generally prohibits automatic knives, with few exceptions.
In states with no ban, they’re still often restricted in schools, federal buildings, or public events.

Out the front knife laws vary greatly, so check state-specific statutes before carrying.

7. Switchblade Laws by State

Switchblades—automatic knives that open with the press of a button—are heavily regulated. Let’s break down some common questions:

Are switchblades illegal in Washington? Yes, except for certain exemptions for law enforcement or collectors.
Are switchblades illegal in Utah? No, Utah law allows automatic knives for most adults.
Are switchblades legal in Utah? Yes, same as above—no state ban.
Are switchblades legal in Idaho? Yes, legal for both open and concealed carry.
Are switchblades illegal in Idaho? No—state law permits them.
Are switchblades legal in Kansas? Yes, state law imposes no major restrictions.

8. Kansas Knife Carry Laws

Kansas is one of the more permissive states. Kansas knife carry laws allow:

Any blade length
Any opening mechanism
Open or concealed carry without a permit

However, local rules might apply to government buildings or schools.

9. Double-Edged Knives

The question “Are double edge knives legal?” is tricky. Some states allow them with no restrictions, while others classify them as dangerous weapons. Even if legal, concealed carry of double-edged knives is often banned.

10. Knife Open Carry Rules

In most states, knife open carry means your blade is visible and not concealed. This often makes it easier to stay legal, especially with larger blades that exceed concealed carry limits.

Tip: Even if open carry is allowed, displaying a large knife in public may draw unwanted police attention.

11. Federal Restrictions

While states set most knife laws, federal law restricts:

Carrying knives onto planes
Possession in federal buildings
Interstate commerce for certain automatic knives

13. Quick FAQ

Is it illegal to carry a pocket knife?
Usually no, but depends on blade length and location.

Are pocket knives legal?
Yes in most states, but some have strict limits.

Are machetes illegal?
Generally legal to own; public carry often restricted.

Knife legal vs. illegal—what’s the difference?
Depends on blade size, type, and intent of use.

Conclusion

Understanding legal carrying knife rules is about more than knowing your favorite blade’s size—it’s about staying within knife carrying laws that differ across jurisdictions. Always check your local regulations, especially when traveling, and remember that a “legal knife” in one state may be an “illegal knife” in another.