What are automatic knives?

An automatic knife is a knife that opens itself when the user pushes a button. Autos fall into two broad categories: side-opening automatic knives and out-the-front automatic knives (or OTFs).

Automatic knives allow for one-handed opening, fast deployment, and easy operation in the absence of fine motor skills. They were born for the battlefield, but make great outdoor, hunting, and EDC knives too!

How an Automatic Knife Works

With side-opening automatic knives, the blade sits in the handle detained by a plunger. A loaded spring, either a coil spring (like on Boker automatic knives) or a leaf spring (like on Italian Stilletto knives) is pushing the blade at all times. When you push the button, it moves the plunger away from the blade and the spring pushes the blade open.

Image based on the Pro-Tech SBR

OTF automatic knives come in two flavors, single-action and double-action. Single-action OTFs (like the Microtech Halo series) are held shut by a plunger, just like a side-opening auto. A compressed spring in the handle pushes the blade forward. When you press the button, the spring shoots the blade out. To close the knife, you have to recharge the spring using the knife’s integrated lever.

Image based on the Microtech Halo VI

Double-action OTFs (like the Guardian Tactical Recon-035) are far more complicated. The blade rests on a rail and is held in place by an internal plunger. When you slide the thumb slide forward, it charges a spring. At the end of the slide, it triggers the internal plunger, allowing the spring to shoot the knife forward on the rails. When it’s open, the blade reengages the plunger and the knife is locked open. The same process happens in reverse when closing.

The Microtech Ultratech shown in the video below has a clear handle that shows its inner workings. Check it out! This particular model is discontinued, but check out a huge variety of Microtech automatic knives and OTFs!

What is the difference between an automatic knife and a switchblade?

All automatic knives are switchblades, but not all switchblades are automatic. A switchblade is any knife that opens automatically by spring force or by force of gravity or inertia. This means gravity knives (like the Reate EXO) and butterfly knives (like the Kershaw Lucha) are switchblades, even though they are not automatic.

Reate EXO Gravity Switchblade Knife

Note, however, that some knives that are described as “switchblades” are neither switchblades nor automatics. Spring Assisted knives are not automatic, even though they seem similar. Spring-assisted knives (like the CRKT Squid XM) use a piece of bent wire that pushes the knife closed. To open the knife, you push a flipper or thumb stud until the spring changes direction, at which point the spring “assists” you in opening the blade. Some self-proclaimed “gravity knives” (like the Paragon Warlock) have a clamshell that holds them closed, so they are not considered switchblades either.

Are automatic knives legal?

Short answer, maybe.

Slightly longer answer, it depends on where you are in the country. Federal laws on switchblades are only binding at the federal level, and municipal and state laws vary. If you live in rural Texas, you can carry any knife your heart desires. If you live in Boston, make sure your knife can’t be opened with one hand and has a sub-3″ blade length.

That said, laws on simple ownership are much more lenient. Almost anywhere, a normal, law-abiding citizen can keep an automatic knife as a desk ornament and the SWAT team will not break down their door.

For more information on automatic knife legality, check out our Switchblade Legality Article and the American Knife and Tool Institute. And for goodness’ sake, don’t take legal advice from us. Go talk to a real lawyer if you’re at all concerned about automatic knife legality.

Why buy an automatic knife?

A good automatic knife can add a splash of tactical flair to a collection and offers some useful benefits as well. People with missing limbs or impaired hand movement love automatics because they don’t require fine motor skills to operate. If you wear gloves, autos will make your life much easier. Automatic knives have a cool factor that can’t be ignored. If an automatic knife sounds like something that could bring you joy and it’s legal for you, why not try one out?