Knife laws in San Diego are essentially California’s knife laws. The city hasn’t added its own blade-length limits or carry restrictions, so what you can carry comes down to the type of knife, whether it’s concealed or openly worn, and where you’re taking it. A folded pocketknife in your pocket is fine. A fixed blade in a visible belt sheath is fine. A locking folder that you’ve opened and hidden under your shirt is a potential felony.
Folding Pocketknives
A standard folding pocketknife is the easiest knife to carry legally. California law lets you carry a folder concealed on your person as long as the blade stays folded. There is no state blade-length limit for a folded pocketknife. A four-inch folder carried closed in your pocket is just as legal as a two-inch one.
The trap is what happens when the blade is open and locked. Under Penal Code 16470, a folding knife with the blade exposed and locked can qualify as a “dirk or dagger,” meaning a knife capable of ready use as a stabbing weapon that could inflict serious injury or death.1California Legislative Information. California Penal Code 16470 Closed in your pocket, that same knife is legal. Opened, locked, and tucked in your waistband under a shirt, it can be charged as a concealed dirk or dagger.
Fixed-Blade Knives
Fixed-blade knives of any length are legal to carry, but they have to be worn openly. Penal Code 20200 says a knife carried in a sheath worn openly and suspended from the waist is not concealed.2California Legislative Information. California Penal Code 20200 A hunting knife visible on your hip is fine. The same knife tucked inside a jacket or a bag crosses into concealed territory and triggers the dirk-or-dagger prohibition.
There is no state maximum blade length for open carry. Walking around downtown with a machete in a visible sheath doesn’t violate the open-carry statute on its own, though it will attract police attention and can lead to other charges depending on the circumstances.
Knives You Can’t Own
Some knives are illegal to make, sell, or possess anywhere in California. Penal Code 16590 lists the generally prohibited weapons, and the knife entries include:
- Ballistic knives (spring-loaded blades that fire forward)
- Belt buckle knives
- Cane swords
- Lipstick case knives
- Writing pen knives
- Air gauge knives
The common thread is deception: these are knives designed to look like something else.3California Legislative Information. California Penal Code 16590
Switchblades
Switchblades have their own rule. Under Penal Code 21510, carrying or possessing a switchblade with a blade of two inches or longer is a misdemeanor. The law also bans keeping one in the passenger or driver area of a vehicle in any public place, and it bans selling or transferring one. A switchblade with a blade under two inches remains legal to carry.4California Legislative Information. California Penal Code 21510
The Concealed Dirk or Dagger Rule
This is the rule that produces most of the unintentional violations in San Diego. Penal Code 21310 makes it illegal to carry a concealed dirk or dagger, and the definition under 16470 is broad enough to cover virtually every fixed-blade knife and any folding knife with its blade exposed and locked open.1California Legislative Information. California Penal Code 16470
A folded pocketknife doesn’t qualify. Open and lock that same blade, then put the knife somewhere out of sight, and it becomes a concealed dirk or dagger under the statute. The offense is a wobbler, which means prosecutors can file it as a misdemeanor or a felony depending on the facts and your record.
Places Where Legal Knives Become Illegal
Even a knife you can legally carry on the sidewalk hits extra restrictions at certain locations.
K-12 Schools
Penal Code 626.10 bans a wide range of knives on any public or private school campus from kindergarten through 12th grade. The list includes any knife with a blade longer than 2½ inches, folding knives with locking blades, and all dirks and daggers.5California Legislative Information. California Penal Code 626.10 Your everyday locking pocketknife, legal on the street, becomes illegal the moment you step onto a school campus.
Colleges and Universities
The college rule under the same statute is slightly different. On UC, Cal State, community college, and private university campuses, the ban covers dirks, daggers, ice picks, and fixed blades longer than 2½ inches. Locking folders are not listed in that subsection, so they are technically legal on college grounds even though they are banned at K-12 schools. Individual campuses can set stricter policies of their own, so check the specific school’s rules.
Government Buildings and Public Meetings
Penal Code 171b prohibits bringing a knife with a blade longer than four inches (fixed, or capable of being locked open) into any state or local government building or any meeting required by law to be open to the public. Any weapon listed as generally prohibited under 16590 is also banned in these locations.6California Legislative Information. California Penal Code 171b San Diego City Hall, county buildings, and public board meetings all fall under this rule.
Courthouses go further. Security screening at the entrance typically prohibits all knives regardless of blade length, and federal buildings and courthouses follow similarly strict federal rules.
Airports and Private Property
Airport security checkpoints prohibit all knives in carry-on bags. Private property owners can set their own knife policies, and posted signs carry legal weight.
Does the City of San Diego Add Its Own Rules?
No. Unlike some California cities, San Diego has not layered separate knife restrictions on top of state law. The municipal code addresses firearms and certain projectile weapons but does not impose separate blade-length limits or carry rules for knives. California doesn’t preempt local knife ordinances, so cities can add their own restrictions and San Diego could change course later. For now, if you follow California state law, you are in compliance inside San Diego city limits.
Penalties
What a knife violation costs you depends on which statute you broke and how prosecutors charge it.
- Switchblade violations under PC 21510 are always misdemeanors, punishable by up to six months in county jail and a fine up to $1,000.
- Concealed dirk or dagger under PC 21310 is a wobbler: up to one year in county jail as a misdemeanor, or 16 months, two years, or three years in state prison as a felony.
- Carrying a knife on school grounds under PC 626.10 is a wobbler: up to one year in county jail as a misdemeanor, or state prison time as a felony.5California Legislative Information. California Penal Code 626.10
- Weapons in government buildings under PC 171b carry up to one year in county jail or state prison.6California Legislative Information. California Penal Code 171b
- Possessing a generally prohibited weapon under PC 16590 is a wobbler: up to one year in county jail as a misdemeanor, or up to three years in state prison as a felony.
If you use a knife in the commission of a separate felony, Penal Code 12022 adds an automatic extra year of consecutive prison time on top of whatever sentence the underlying crime carries. That enhancement applies even if the knife itself was legal to possess.7California Legislative Information. California Penal Code 12022
Flying or Driving Into San Diego
San Diego International Airport follows TSA rules, which prohibit all knives in carry-on bags. The only exceptions are rounded butter knives and plastic cutlery. There is no minimum blade length that makes a knife acceptable in a carry-on.8Transportation Security Administration. Knives You can pack knives in checked luggage; sheath fixed blades and close folders to protect baggage handlers.
When you drive into California, your knives are governed by California rules from the state line onward. A switchblade with a blade of two inches or longer in your glove box or center console violates Penal Code 21510 even if it was legal where you started your trip. Fixed-blade knives stored in a bag or trunk where they aren’t readily accessible are generally not considered carried on the person, but if you plan to have one on your body at any point, keep it in a visible sheath.