A utility knife (also called a box cutter, a boxcutter, a razor blade knife, a carpet knife, or a stationery knife) is a common tool used in various trades and crafts for a variety of purposes.
Such a knife generally consists of a simple and cheap holder, typically flat, approximately one inch (25 mm) wide and three to four inches (75 to 100 mm) long, and typically made of either metal or plastic. Some use standard razor blades, others specialised double-ended blades as in the illustration. The user can manually adjust how far the blade extends from the handle, so that for example the knife can be used to cut the tape sealing a package without damaging the contents of the package. When the blade becomes dull, it can be quickly reversed or switched for a new one. Spare or used blades are stored in the hollow handle of some models, and can be accessed by removing a screw and opening the handle. Other models feature a quick-change mechanism that allows replacing the blade without tools, as well as a flip-out blade storage tray. This type of tool is known in British English, Australian English, New Zealand English and Dutch as a Stanley knife, a genericized trademark named after one of the manufacturers to create this kind of implement.
The blades for a utility knife come in both double and single ended versions, and are interchangeable with many, but not all of the later copies. Specialized blades also exist for cutting string, linoleum and other purposes. Spare or used blades may be stored in the handle in some models.
Another style is a snap-off utility knife that contains a long, segmented blade that slides out from it. As the endmost edge becomes dull, it can be snapped off from the rest of the blade, exposing the next section, which is sharp and ready for use, increasing safety. When all the individual segments are used, it is thrown away or a replacement blade is inserted. This design was introduced by OLFA® Corporation in 1956 as the world's first snap-off blade and was inspired from analyzing the sharp cutting edge produced when glass is broken and how pieces of a chocolate bar break into segments.
Fixed blade versions, usually about the size of a pencil, are widely used for handcrafts and model making and are best suited for cutting thin, lightweight materials.
A style that is often used for the cutting of boxes consists of a simple sleeve around a rectangular handle into which single-edge razor blades can be inserted. The sleeve slides up and down on the handle, holding the blade in place during use and covering the blade when not in use. The blade holder is designed to expose just enough edge to cut through one layer of corrugated fiberboard, to minimize chances of damaging contents of cardboard boxes.
Although such knives are not usually regarded as weapons, it was suggested by United States government officials that "box-cutter knives" were used in the September 11, 2001, terrorist attacks against that country. The exact design of the knives actually used is unclear. (See Airport security repercussions due to the September 11 attacks for further discussion.)
They have also been used by minor criminals in muggings, and some schools ban their possession on school grounds. Former New York City mayor Rudy Giuliani initiated a campaign against the sale of box-cutter knives to young people in the 1990s.
In Australia, it is illegal to sell a cutting implement such as a utility knife to anyone under 16 years of age, and proof of age is often demanded of purchasers.
The knives have been used within football hooliganism for some time, as they are able to scar without killing, something many hooligans are hesitant to do. This fact was made famous in the film The Football Factory.