A major

A major (or the key of A) is a major scale based on A, with the pitches A, B, C♯, D, E, F♯, and G♯. Its key signature has three sharps. Its relative minor is F-sharp minor and its parallel minor is A minor. The key of A major is the only key where the Neapolitan sixth chord on (i.e. the flattened supertonic) requires both a flat and a natural accidental.

The A major scale is:

In the treble, alto, and bass clefs, the G♯ in the key signature is placed higher than C♯. However, in the tenor clef, it would require a ledger line and so G♯ is placed lower than C♯.

Scale degree chords

 * Tonic – A major
 * Supertonic – B minor
 * Mediant – C-sharp minor
 * Subdominant – D major
 * Dominant – E major
 * Submediant – F-sharp minor
 * Leading-tone – G-sharp diminished

History
Although not as rare in the symphonic literature as sharper keys (those containing more than three sharps), symphonies in A major are less common than in keys with fewer sharps such as D major or G major. Beethoven's Symphony No. 7, Bruckner's Symphony No. 6 and Mendelssohn's Symphony No. 4 comprise a nearly complete list of symphonies in this key in the Romantic era. Mozart's Clarinet Concerto and Clarinet Quintet are both in A major, along with his 23rd Piano Concerto, and generally Mozart was more likely to use clarinets in A major than in any other key besides E-flat major. Moreover, the climax part of Tchaikovsky's Violin Concerto is also in A major.

The key of A occurs frequently in chamber music and other music for strings, which favor sharp keys. Franz Schubert's Trout Quintet and Antonín Dvořák's Piano Quintet No. 2 are both in A major. Johannes Brahms, César Franck, and Gabriel Fauré wrote violin sonatas in A major. In connection to Beethoven's Kreutzer Sonata, Peter Cropper said that A major "is the fullest sounding key for the violin."

According to Christian Friedrich Daniel Schubart, A major is a key suitable for "declarations of innocent love, ... hope of seeing one's beloved again when parting; youthful cheerfulness and trust in God."

For orchestral works in A major, the timpani are typically set to A and E a fifth apart, rather than a fourth apart as for most other keys. Hector Berlioz complained about the custom of his day in which timpani tuned to A and E a fifth apart were notated C and G a fourth apart, a custom which survived as late as the music of Franz Berwald.

Notable compositions in A major

 * Antonio Vivaldi
 * Trio Sonata, Op. 1/9 RV 75
 * Violin Sonata, Op. 2/2 RV 31
 * concerto for two violins, Op. 3/5 RV 519
 * concerto for violin, Op. 4/5 RV 347
 * Violin Sonata, Op. 5/2 RV 30
 * concerto for violin, Op. 9/2 RV 345
 * concerto for violin, Op. 9/6 RV 348
 * concerto for violin, Op. 11/3 RV 336
 * Georg Philipp Telemann
 * Fantasia for flute solo, No. 1
 * Fantasia for violin solo, No. 5
 * Fantasia for viola da gamba solo, No. 8
 * Sonata for two flutes or two violins, No. 3
 * Johann Sebastian Bach
 * English Suite No. 1, BWV 806
 * Wolfgang Amadeus Mozart
 * Violin Concerto No. 5, K. 219
 * Symphony No. 29, K. 201
 * Symphony No. 21, K. 134
 * Violin Sonata No. 22, K. 305
 * Piano Sonata No. 11, K. 331
 * String Quartet No. 18, K. 464
 * Piano Concerto No. 23, K. 488
 * Là ci darem la mano, duettino form Don Giovanni, K. 527
 * Clarinet Quintet, K. 581
 * Clarinet Concerto, K. 622
 * Ludwig van Beethoven
 * Symphony No. 7, Op. 92
 * Piano Sonata No. 2, Op. 2/2
 * Piano Sonata No. 28, Op. 101
 * Violin Sonata No. 6, Op. 30/1
 * Violin Sonata No. 9, Op. 47
 * Cello Sonata No. 3, Op. 69
 * String Quartet No. 5, Op. 18/5
 * Franz Schubert
 * Trout Quintet
 * Piano Sonata, D 664
 * Piano Sonata No. 20, D. 959
 * Felix Mendelssohn
 * Symphony No. 4, Op. 90 ("Italian")
 * Organ Sonata, Op. 65, No. 3
 * Frédéric Chopin
 * Polonaise, Op. 40/1 ("Military")
 * Prelude, Op. 28/7
 * Franz Liszt
 * Piano Concerto No. 2, S.125
 * Johannes Brahms
 * Serenade No. 2, Op. 16
 * Violin Sonata No. 2, Op. 100 ("Thun")
 * Piano Quartet No. 2, Op. 26
 * César Franck
 * Violin Sonata
 * Anton Bruckner
 * Symphony No. 6
 * Émile Waldteufel
 * Les Patineurs waltz, Op. 183
 * Sergei Prokofiev
 * Piano Sonata No. 6, Op. 82
 * Dmitri Shostakovich
 * String Quartet No. 2, Op. 68
 * Symphony No. 15, Op. 141