A piano trio is a group that includes a piano and two other instruments, such as a violin and a cello, or a musical piece written for such a group. It is one of the most common types of classical chamber music. The term can also describe a group of musicians who often perform this type of music together; examples of well-known piano trios are listed below.

The term "piano trio" is also used in jazz music to describe a group that usually includes a pianist, a bassist, and a drummer. Sometimes, a guitarist or a saxophonist may be part of the group instead.

Form

Works named "Piano Trio" usually follow a structure similar to a sonata. Originally, they had three movements, though some of Joseph Haydn’s works had only two. In five late compositions, Wolfgang Amadeus Mozart is credited with changing the accompanied keyboard sonata—where the cello often plays the same notes as the keyboard’s left hand—into a well-balanced trio that became a central form of chamber music. By the early 19th century, especially with Ludwig van Beethoven, this genre was often written in four movements instead. Piano trios based on the sonata tradition share similar themes to other works of their time and often show similarities to symphonic music, with movements arranged according to the composer’s understanding of sonata form.

During the Classical era, playing music at home made the piano trio a popular genre for arranging other works. For example, Beethoven adapted his first two symphonies for piano trio. This means many pieces for piano, violin, and cello exist that are not officially called or numbered as piano trios but still belong to this genre. These include single movements and sets of variations, such as Beethoven’s Kakadu Variations Op. 121a and Variations in E flat major Op. 44.

After the Classical era, many works for piano and two instruments were written that did not follow the sonata tradition or were arrangements of other pieces. Some of these individual works are commonly performed in concerts, such as Joseph Suk’s Elegy.

The role of the three instruments

During the Classical era, piano trios focus heavily on the piano. Haydn's trios are called "accompanied sonatas" because the piano plays a central role. The violin plays the melody only sometimes, and when it does, the piano often repeats the same notes. The cello part is less important, usually playing the same bass line as the piano. This was likely because pianos in Haydn's time had a weak, delicate sound and needed other instruments to add strength. Mozart's five later trios (K. 496, etc.) show the form becoming more balanced, with equal attention given to all three instruments in a musical conversation.

Beethoven's trios continued the goals Mozart set. The idea of equal importance among instruments was not fully achieved, and how much equality was shown varied between pieces and even within the same piece.

Today, real performances of older trios use instruments from the same time period as the original compositions.

Other combinations

Some unusual combinations of instruments have inspired some important musical pieces.

• Haydn wrote three trios for flute, cello, and piano (H. 15/15-17), a combination for which Carl Maria von Weber also wrote one work (op. 63).
• Beethoven wrote his Trio in G major, WoO 37 (1786) for flute, bassoon, and piano.
• Mikhail Glinka wrote his Trio pathétique in D minor for clarinet, bassoon, and piano, but it is also sometimes played with a violin or cello instead of the clarinet or bassoon.
• Francis Poulenc wrote a Trio for oboe, bassoon, and piano, op. 43 (1926).
• The Horn-violin-piano trio is shown in Brahms' Trio Op. 40 in E flat and György Ligeti's 1982 Trio for Violin, Horn, and Piano.
• Trios with clarinet include important works such as Mozart's Kegelstatt Trio and pieces by Beethoven, Brahms, and Bartók; many more are listed in Clarinet-violin-piano trio, Clarinet-viola-piano trio, and Clarinet-cello-piano trio.
• Ignaz Lachner wrote all of his six piano trios for violin, viola, and piano.
• The Indonesian composer Ananda Sukarlan has written several trios with piano that use rare combinations, such as Menage a Trois for flute, viola, and piano, Mutahariana for clarinet, French horn, and piano, Communication Breakdown for flute, bassoon, and piano, or Frida's Monkeys for oboe, violin, and piano.
• The jazz trio formation of saxophone, piano, and percussion has been used as a different type of "piano trio" in contemporary classical music. Trio Accanto, starting in 1994, commissioned more than 100 works for this combination. Other trios have also been formed to perform this type of music.

Example piano trios, extant and defunct

Some of the most well-known piano trios include:

• Altenberg Trio (Austria)
• Amatis Trio (the Netherlands)
• ATOS Trio [de] (Berlin, Germany)
• Maria Baptist [jazz] Trio (Berlin, Germany)
• Istomin-Stern-Rose Trio, made up of Eugene Istomin, Isaac Stern, and Leonard Rose (United States)
• A trio including Alfred Cortot, Jacques Thibaud, and Pablo Casals, earlier in the 20th century
• The Spivakovsky Trio, including Jascha Spivakovsky, Tossy Spivakovsky, and Edmund Kurtz, earlier in the 20th century
• The Kalichstein-Laredo-Robinson Trio (United States)
• The Beaux Arts Trio (United States), which started a new way of using the same musicians for every performance; no longer active
• The Sitkovetsky Trio (United Kingdom), including Alexander Sitkovetsky, Wu Qian, and Isang Enders
• Trio di Trieste (Italy), including Dario De Rosa, Renato Zanettovich, and Libero Lana/Amedeo Baldovino; no longer active
• The "Ax-Kim-Ma" trio, including Emanuel Ax, Young-Uck Kim, and Yo-Yo Ma (United States)
• Eroica Trio (United States)
• Ahn Trio (United States/Korea)
• The Borodin Trio (United States)
• Trio Fontenay (Germany)
• Trio Céleste (United States), including Kevin Kwan Loucks, Iryna Krechkovsky, and Ross Gasworth
• Suk Trio (Czech Republic)
• The Florestan Trio (United Kingdom)
• The Greenwich Trio (United Kingdom)
• The Gryphon Trio (Canada)
• The Oberlin Trio (United States)
• The Alma Trio (United States)
• Trio Vega (Spain)
• Trio Kandinsky (United States)
• Trio Wanderer (France)
• Haydn Trio Eisenstadt (Austria): Harald Kosik, Hannes Gradwohl, Bernd Gradwohl/Verena Stourzh
• Bamberg Trio (Germany)
• Petrof Piano Trio (Czech Republic)
• Manhattan Piano Trio (United States)
• Spirale Piano Trio (Belgium)
• Xonor Trio (United States)
• Vanic Trio (United States)
• Vienna Piano Trio (Austria)
• Stuttgart Piano Trio (Germany)
• The Dutch Trio (Germany/The Netherlands)

Famous works for piano trio

• Anton Arensky's Piano Trio No. 1 in D minor
• Ludwig van Beethoven's trios, including Piano Trio No. 7 in B-flat major "Archduke," Op. 97
• Johannes Brahms's Piano Trios No. 1 in B major, Op. 8, No. 2 in C major, Op. 87, and No. 3 in C minor, Op. 101
• Elliott Carter's Epigrams (2012)
• Frédéric Chopin's Piano Trio in G minor, Op. 8
• Antonín Dvořák's Piano Trio No. 4 in E minor ("Dumky"), Op. 90
• Gabriel Fauré's piano trio, Op. 120
• Joseph Haydn's 45 piano trios, especially those written from the mid-1780s onward
• Charles Ives's Piano Trio, 1911
• Franz Liszt's Hungarian Rhapsodies No. 9 and No. 12
• Felix Mendelssohn's two piano trios
• Wolfgang Amadeus Mozart's piano trios, especially No. 3, 4, and 5
• Sergei Rachmaninoff's Elegiac Trios No. 1 in G minor and No. 2 in D minor
• Maurice Ravel's Trio for Piano, Violin, and Cello
• Camille Saint-Saëns's Piano Trio No. 1 and Piano Trio No. 2
• Franz Schubert's Piano Trio No. 1 and No. 2
• Clara Schumann's Piano Trio
• Robert Schumann's Piano Trio No. 1 in D minor and Piano Trio No. 3 in G minor
• Dmitri Shostakovich's Piano Trio No. 2 in E minor
• Bedřich Smetana's Trio for Piano, Violin, and Cello
• Pyotr Ilyich Tchaikovsky's Piano Trio in A minor, Op. 50