The Symphony No. 4 in D major, K. 19, by Wolfgang Amadeus Mozart was composed in London during the Mozart family's Grand Tour of Europe in 1765, when Mozart was nine years old.
The Symphony No. 8 in D major,, by Wolfgang Amadeus Mozart is dated December 13, 1768. Mozart wrote the symphony in Vienna, when he was twelve years old, at a time when he and his family were already due to have returned home to Salzburg. In a letter to his friend in Salzburg, Lorenz Hagenauer, Leopold Mozart says of the delay that "we could not bring our affairs to a conclusion earlier, even though I endeavored strenuously to do so." The autograph of the Symphony No. 8 is today preserved in the Staatsbibliothek Preusischer Kulturbesitz in Berlin.
Symphony No. 6 in F major, K. 43, was composed by Wolfgang Amadeus Mozart in 1767. According to Alfred Einstein in his 1937 revision of the Köchel catalogue, the symphony was probably begun in Vienna and completed in Olomouc, a Moravian city to which the Mozart family fled to escape a Viennese smallpox epidemic; see Mozart and smallpox.
Symphony No. 7 in D major, K. 45, by Wolfgang Amadeus Mozart, was completed in Vienna in January 1768 after the family's return from a visit to Olomouc and Brno in Moravia. The symphony is in four movements. Its first performance was probably at a private concert. The symphony was reworked to become the overture to Mozart's opera, La finta semplice, K. 51, composed and performed later that year, and the overture itself was subsequently adapted further to create a new symphony, known in the Köchel 1964 (K6) catalogue as K. 46a. The autograph of the score is preserved in the Berlin State Library.
Symphony No. 9 in C major, K. 73/75a, by Wolfgang Amadeus Mozart, has an uncertain provenance. The most likely date of its composition appears to be late 1769 or early 1770 during Mozart's first Italian journey, although some authorities have dated it "probably not before early summer 1772". It may have been started in Salzburg, before the first Italian journey began, and completed during the trip.
Symphony No. 12 in G major, K. 110/75b, by Wolfgang Amadeus Mozart, was composed in Salzburg in the summer of 1771. The symphony was apparently prepared in anticipation of Mozart's second Italian journey, which was to take place between August and December 1771. The symphony is in four movements, the opening allegro being the longest movement that Mozart had written to that date. It is the first of a group of works "painted on a larger canvas and achieving a greater individuality than his earlier exuberant pieces".
Symphony No. 13 in F major, K. 112, by Wolfgang Amadeus Mozart, was written in Milan during his second journey to Italy in the autumn of 1771. The symphony is in four movements, the second of which is scored for strings alone. The third movement minuet may have been written earlier, and then incorporated into the symphony—the autograph manuscript shows the minuet copied in Leopold's hand. Nicholas Kenyon describes Symphony No. 13 as the last in "conventional mode"—thereafter "we are in the beginnings of a different world."
Symphony No. 11 in D major, K. 84/73q, was at one time considered unquestionably to be the work of Wolfgang Amadeus Mozart. Its status has, however, been challenged, and remains uncertain. It is believed to date from 1770, and may have been written in Milan or Bologna, if it is a genuine Mozart work. An early manuscript from Vienna attributes the work to Wolfgang, but nineteenth-century copies of the score attribute it respectively to Leopold Mozart and to Carl Dittersdorf. Neal Zaslaw writes: "A comparison of the results of two stylistic analyses of the work's first movement with analyses of unquestionably genuine first movements of the period by the three composers suggests that Wolfgang is the most likely of the three to have been the composer of K73q".
The Symphony in F major "No. 42", K. 75, was written by Wolfgang Amadeus Mozart probably around March to August 1771 in Salzburg.
The Symphony in F major "No. 43", K. 76/42a, was probably written by Wolfgang Amadeus Mozart.
The Symphony in D major "No. 48", K. 111+120, was composed by Wolfgang Amadeus Mozart in 1771. The first two movements are from the overture to the opera Ascanio in Alba, K. 111, and the last movement, K. 120/111a, was composed separately.
The Symphony in D major "No. 50", K. 161/141a, was composed by Wolfgang Amadeus Mozart in 1772. The first two movements are from the overture to the opera Il sogno di Scipione, K. 126, and the last movement, K. 163, was composed separately. Köchel gave the entire work the number K. 161.
The Symphony in D major "No. 51", K. 196+121 (207a, was composed by Wolfgang Amadeus Mozart in 1774–1775. The first two movements are from the overture to the opera La finta giardiniera, K. 196, and the last movement, K. 121/207a, was composed separately in 1775.
The Symphony in B♭ major "No. 55", K. Anh. 214/45b, was probably written by Wolfgang Amadeus Mozart in early 1768 in Salzburg.
The Symphony in C major "No. 46", K. 96/111b, was probably written by Wolfgang Amadeus Mozart in 1771 in Milan.
The Symphony in D major "No. 47", K. 97/73m, was probably written by Wolfgang Amadeus Mozart in 1770 in Rome.
The Symphony in F major "No. 56", K. 98/Anh.C 11.04, was once thought to have been written by Wolfgang Amadeus Mozart, but today is regarded as spurious. As of 2009, it is the only one of Mozart's symphonies published in the Alte Mozart-Ausgabe that has never been recorded. It is not included in the Neue Mozart-Ausgabe.
The Symphony in D major "No. 44", K. 81/73l, may have been written by Wolfgang Amadeus Mozart in 1770 in Rome, although it has sometimes also been attributed to his father Leopold Mozart. It is now also catalogued as Eisen D 14 in Cliff Eisen's catalogue of Leopold Mozart's symphonies.
The Symphony in B♭ major "No. 54", K. Anh. 216/74g/Anh.C 11.03, may have been written by Wolfgang Amadeus Mozart in 1771, in Salzburg.
The Symphony in A minor "Odense", K. Anh. 220/16a, was formerly attributed to Wolfgang Amadeus Mozart. If the Odense Symphony had truly been Mozart's, it would be among only three of Mozart's symphonies to be written in a minor key. It is now considered certain that the symphony is not by Mozart.
