Tuning

Violins are tuned by turning the pegs in the pegbox under the scroll, or by adjusting the fine tuner screws at the tailpiece. All violins have pegs; fine tuners (also called fine adjusters) are optional. Most fine tuners consist of a metal screw that moves a lever to which the string is attached. They permit very small pitch adjustments with much more ease than the pegs.

Fine tuners are usually used with solid metal or composite strings that may be difficult to tune with pegs alone; they are not used with gut strings, which are more elastic and do not respond adequately to the very small movements of fine tuners. Some violinists have fine tuners on all 4 strings; most classical players have only a single fine tuner on the E string.

To tune a violin, the A string is first tuned to a standard pitch (usually 440 Hz), using either a tuning device or another instrument. (When accompanying a fixed-pitch instrument such as a piano or accordion, the violin tunes to it.) The other strings are then tuned against each other in intervals of perfect fifths by bowing them in pairs. A minutely higher tuning is sometimes employed for solo playing to give the instrument a brighter sound; conversely, Baroque music is sometimes played using lower tunings to make the violin's sound more gentle. After tuning, the instrument's bridge may be examined to ensure that it is standing straight and centered between the inner nicks of the f-holes; a crooked bridge may significantly affect the sound of an otherwise well-made violin.

The tuning G-D-A-E is used for most violin music. Other tunings are occasionally employed; the G string, for example, can be tuned up to A. The use of nonstandard tunings in classical music is known as scordatura; in some folk styles, it is called "cross-tuning." One famous example of scordatura in classical music is Saint-Saëns' Danse Macabre, where the solo violin's E string is tuned down to E flat to impart an eerie dissonance to the composition. Another example would be in the third movement of Contrasts, by Béla Bartók, where the E string is tuned down to E flat and the G tuned to a G sharp.
In Indian classical music and Indian light music, the violin is likely to be tuned to D#-A#-D#-A# in the South Indian style. As there is no concept of absolute pitch in Indian classical music, any convenient tuning maintaining these relative pitch intervals between the strings can be used. Another prevalent tuning with these intervals is F-B♭-F-B♭, which corresponds to Sa-Pa-Sa-Pa in the Indian carnatic classical music style. In the North Indian "Hindustani" style, the tuning is usually Pa-Sa-Pa-Sa instead of Sa-Pa-Sa-Pa. This could correspond to B♭-F-B♭-F, for instance.

While most violins have four strings, there are some instruments with five strings,[14] six, or even seven. The extra strings on such violins typically are lower in pitch than the G-string; these strings are usually tuned to C, F, and B flat. If the instrument's playing length, or string length from nut to bridge, is equal to that of an ordinary full-scale violin i.e., a bit less than 13 inches (330 mm), then it may be properly termed a violin. Some such instruments are somewhat longer and should be regarded as violas. Violins with five strings or more are often used in jazz or folk music.