A pencil sharpener (or pencil pointer, or in Ireland a parer or topper)^[1] is a tool for sharpening a pencil's writing point by shaving away its worn surface. Pencil sharpeners may be operated manually or by an electric motor. It is common for many sharpeners to have a casing around them, which can be removed for emptying the pencil shavings debris into a bin.

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Before the development of dedicated pencil sharpeners, a pencil was sharpened by whittling with a knife.

The development of pencil sharpeners began in France when a French book from 1822 reported in detail about an invention of Mr. C. A. Boucher (Paris) for the construction of a pencil sharpener. He was working with pantographs and apparently needed a device to precisely sharpen the pencils.^[2][3] The device of Mr. Boucher was technically sensible and functional. His idea was also internationally known and recognized, as shown by corresponding reports in German literature at this time.^[4] But Mr. Boucher had not applied a patent for his pencil sharpener. Commercial use of his inventions is unlikely.

French mathematician Bernard Lassimonne (Limoges) applied for the world's first patent (French patent #2444) on a pencil sharpener in 1828.^[5] Pencil sharpener devices using his patent were actually produced and sold by Binant, a shop for painting accessories in Paris.^[3] In 1833 in England, Cooper & Eckstein patented the so-called Styloxynon, a simple device consisting of two sharp files set together at right angle in a small block of rosewood.^[6][7] This is the oldest pencil sharpener that has surviving examples.^[8]

In the 1830s and 1840s, some French people, all based in Paris, were engaged in construction of simple pencil sharpening tools, like François Joseph Lahausse.^[9] These devices were partially sold, but without supra-regional significance. In 1847 the French nobleman Thierry des Estivaux invented a simple hand-held pencil sharpener in its recognizable modern form.^[10][11] The first American pencil sharpener was patented by Walter Kittredge Foster of Bangor, Maine in 1855.^[12] He founded a company – the first pencil sharpener company in the world – and produced such small hand-held pencil sharpeners in a large amount. Only a few years later the sharpeners were sold also in Europe as "American pencil sharpeners".^[13]

At the end of the 19th century especially in the United States, pencil sharpeners with various mechanisms had been developed and put on the market. These devices were often heavy and intended for use in offices. Examples are the Perfect Pencil Pointer (Goodell. Co.), the GEM Pencil Sharpener (by Gould & Cook Co.), the Planetary Pencil Sharpener (A. B. Dick Co.), all from the US or the Jupiter (Guhl & Harbeck Co.) from Germany.^[14] At the beginning of the 20th century the company Automatic Pencil Sharpener Co. (APSCO) was founded and brought out the US Automatic Pencil Sharpener after 1907,^[14] which dominated in those years. Later they sold machines with milling mechanisms, such as the Climax, Dexter, Wizard, and Junior models.^[15] APSCO became in the next few decades the largest pencil sharpening machine producer in the world and together with a few other US companies, it dominated the market.

Electric pencil sharpeners for offices have been made since at least 1917. A school teacher, Neil Carruthers, brought electric sharpeners from his visit to USA back to his town of Whitehaven for use in schools at the end of the Victorian Era.^[16]

In May 2011, tourism officials in Logan, Ohio put on display, in its regional welcome center, hundreds of pencil sharpeners which had been collected by Rev. Paul Johnson, an Ohio minister who died in 2010. Johnson, a World War II veteran, had kept his collection of more than 3,400 sharpeners in a small shed, outside his home in Carbon Hill in southeast Ohio. He had started collecting after his wife gave him a few pencil sharpeners as a gift in the late 1980s and kept them organized into categories, including cats, Christmas, and Disneyland.^[17]

The oldest surviving electric pencil sharpener is the Boston Polar Club pencil sharpener, introduced around 1936.^[19] Electric pencil sharpeners work on the same principle as manual ones, but one or more flat-bladed or cylindrical cutters are rotated by an electric motor.^[16] Some electric pencil sharpeners are powered by batteries rather than being plugged into a building's electrical system, making them more portable.

Auto-stop electric pencil sharpeners are able to sense when the tip of the pencil is long enough, so they stop automatically. In basic automatic pencil sharpeners, the lead may become too long and break, and so users must be careful to supervise the operation.

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Specialized sharpeners are available that operate on non-standard sizes of pencil-shaped markers, such as wax crayons used in primary schools. Sharpeners that have two openings, one for normal pencils and one for larger crayons, are fairly common. Sharpeners with a single blade for use on wax crayons are available, and sometimes included in boxes of crayons. These often have plastic blades, which are adequate for the soft wax.

An artist's or draftsman's pencil sharpener leaves the graphite untouched and sharpens only the wood (some models can switch from standard to wood-only by an adjustment). The graphite lead is then honed to a sharp point with a lead pointer, which sharpens only the lead without wood. Lead pointers are also used with mechanical leadholders, with thicker diameter leads like 2 mm which have removable/refillable leads. Some sharpeners which function as a long point sharpener, have a second hole in which the blade sharpens the untouched graphite to a long, more precise point than would be otherwise possible using a single hole long point sharpener.

Carpenters may use carpenter pencils, the flattened shape of which stops them from rolling away, while still providing a constant line width. These pencils were traditionally sharpened with tools conveniently to hand, such as a plane or sandpaper. Rotating pencil sharpeners are now available for these pencils, in which a rotating plastic collar holds the pencil in position, although they then sharpen to the usual conical point as for a round pencil, abandoning some distinctive aspects of the carpenter's pencil. Alternatively, a special carpenter's pencil sharpener can be used, which has a sliding mechanism that leaves flat facets on the lead, in a manner similar to hand sharpening with a sharp knife.

Mechanical pencils with thin diameter leads dispense the graphite lead progressively during use and thus do not require sharpening; such pencils are sometimes called "self-sharpening". A type of mechanical pencil has a rotating gear mechanism which rotates the lead slightly every time the lead is lifted off the paper, helping to maintain a consistent, sharp point. If a finer or broader line is needed, a separate mechanical pencil using a lead with a different diameter is required.

• Hand-cranked planetary sharpener, with cover in place
• Hand-cranked planetary sharpener from 1950 to 1960, with cover removed
• Hand-cranked planetary sharpener with spring-driven pencil holder. The small knob behind the crank is a sharpness regulator.
• AC-powered electric pencil sharpener. The mechanism is similar to the planetary sharpener, except there is a motor instead of a crank.
• Battery-operated sharpener
• Ecologically manufactured pencil sharpener made of wood
• A wall-mounted planetary sharpener (casing removed to reveal the mechanism)
• Prism sharpener with two holes for two sizes of pencils

• Mechanical pencil
• Pencil Sharpener Museum